Labels are like tags you can add to emails you send or receive. You can add more than one Label to an email. It also has an ability to add colors to Labels.
Directions:
Head to your settings (the gear icon at the top right), then click All Settings
Click Labels, then scroll down under Label, click Create new label
You can manage your incoming mail using Gmail’s filters to send email to a label, or archive, delete, star, or automatically forward your mail.
Open Gmail.
In the search box at the top, click the Down arrow.
Enter your search criteria. If you want to check that your search worked correctly, see what emails show up by clicking Search.
At the bottom of the search window, click Create filter.
Choose what you’d like the filter to do.
Click Create filter.
Note: When you create a filter to forward messages, only new messages will be affected. Additionally, when someone replies to a message you've filtered, the reply will only be filtered if it meets the same search criteria.
Use a particular message to create a filter
Open Gmail.
Check the checkbox next to the email you want.
Click More (Three dots).
Click Filter messages like these.
Enter your filter criteria.
Click Create filter.
Open Gmail.
At the top right, click Settings (Gear icon) > See all settings.
Click Filters and Blocked Addresses.
Find the filter you'd like to change.
Click Edit or Delete to remove the filter. If you’re editing the filter, click Continue when you’re done editing.
Click Update filter or OK.
If you're a filter pro and have a great filter system that you want to use in another account or share with a friend, you can export and import filters.
Open Gmail.
At the top right, click Settings (Gear icon) > See all settings.
Click Filters and Blocked Addresses.
Check the box next to the filter.
At the bottom of the page, click Export.
This will give you a .xml file, which you can edit in a text editor if you'd like.
At the bottom of the page, click Import filters.
Choose the file with the filter you'd like to import.
Click Open file.
Click Create filters.
Five options to organize your inbox.
Directions:
Head to your settings (the gear icon at the top right), then click All Settings
Click the dropdown next to inbox type
Descriptions:
Default: It shows the emails in the order that they came in — the layout we see everyday.
Important first: Gmail uses its own prediction to determine which emails are important, and places them at the top of your inbox with a yellow marker. Everything else goes below that.
Unread first: This setting displays unread emails above recent emails. This is especially helpful if you use the read/unread as a to-do list.
Starred first: This is for the ones who use stars to prioritize their inbox. The starred messages appear first, followed by everything else.
Priority Inbox: Gmail learns what kind of emails you interact with the most, and puts them at the top of your inbox.
The Nudge is an algorithm in Gmail which brings emails back to the top of your inbox when a reply hasn’t been sent by you or a recipient. It is great if you need constant reminders to send replies or follow-ups to important emails.
Directions:
Head to your settings (the gear icon at the top right), then click All Settings
Under General tab, scroll down to Nudges then tick the boxes
Description:
Suggest emails to reply to: Emails you might have forgotten to respond to will appear at the top of your inbox.
Suggest emails to follow up on: Sent emails you might need to follow up on will appear at the top of your inbox.
Gmail has an Undo Send option that allows you to “unsend” emails for up to 30 seconds after it’s been sent.
Directions:
Head to your settings (the gear icon at the top right), then click All Settings
Under General tab, scroll down to Undo send then choose the cancellation period.
Save all changes
This option removes emails from your inbox only to bring them back later, which is perfect for anything you need to act on eventually but can’t act on right now.
Directions:
In your Inbox, click the clock icon on the right of the email
The email shows back up in your Inbox when the time is up
You can schedule your emails to send at a later time. Scheduled emails may be sent a few minutes after the scheduled time.
Important: Your emails will be sent based on the timezone you schedule them in.
Directions:
At the top left, click Compose
Create your email
At the bottom left next to "Send," click Schedule send. Note: You can have up to 100 scheduled emails.
View, change or cancel scheduled emails
At the left panel, click Scheduled.
Select the email you want to change.
At the top right of your email, click Cancel send or Create your changes. Note: When you cancel a scheduled email, it becomes a draft.
Source: Gmail Help