In every (grammatically complete) sentence, there is always a subject and a verb:
Subject: the thing that sentence is about; the focus of the sentence, e.g. The crocodile is snapping at my heels.
Verb: the action that the subject is taking; the thing the subject is ‘doing’, e.g The crocodile is snapping at my heels.
There may also be an object: a thing (or person) that is affected by the subject, e.g. The crocodile is snapping at my heels. (Some sentences don’t require an object, e.g. The crocodile is eating.)
The verb form needs to match (‘agree with’) the ‘number’ of nouns.
If there is just one noun or a singular noun as the subject, the verb needs to be in the singular form, e.g. The crocodile charges at me.
If there is more than one noun because the noun is a plural or there are two or more nouns in the subject (i.e. a compound subject), the verb needs to be in the plural form, e.g.
The crocodiles charge at me.
The crocodile and his hungry friend charge at me.
Extra information:
In almost all cases, collective nouns are singular so require the singular form of the verb, e.g. The float of crocodile charges at me
Using the plural verb form with a collective noun is a common mistake, e.g. The float of crocodiles *charge* at me or The whole team *are* running from the crocodile = both incorrect)
The words everyone, everybody, no-one and nobody are singular.
When an extra element is added to a singular noun using phrases like as well as and together with, the verb remains singular, e.g. The crocodile, along with its hungry friend, crawled toward me.