Strength measures bodily power, athletic training, and the extent to which you can exert raw physical force.
Athletics: Your Strength (Athletics) check covers difficult situations you encounter while climbing, jumping, or swimming.
Small Weapons: Knives, daggers, handaxe.
Medium Weapons: Mace, Morning Star, Longsword, Flail
Large Weapons: Greatsword, Halberd, Lance, Warhammer
Dexterity measures agility, reflexes, and balance.
Acrobatics: Covers your attempt to stay on your feet in a tricky situation, such as when you're trying to run across a sheet of ice, balance on a tightrope, or stay upright on a rocking ship's deck.
Sleight of Hand: Whenever you attempt an act of legerdemain or manual trickery, such as planting something on someone else or concealing an object on your person, stealing, etc.
Stealth: When you attempt to conceal yourself from enemies, slink past guards, slip away without being noticed, or sneak up on someone without being seen or heard.
Intelligence measures mental acuity, accuracy of recall, and the ability to reason.
Arcana: Measures your ability to recall lore about spells, magic items, eldritch symbols, magical traditions, the planes of existence, and the inhabitants of those planes.
History: Measures your ability to recall lore about historical events, legendary people, ancient kingdoms, past disputes, recent wars, and lost civilizations.
Investigation: When you look around for clues and make deductions based on those clues.
Nature: Measures your ability to recall lore about terrain, plants and animals, the weather, and natural cycles.
Religion: Measures your ability to recall lore about deities, rites and prayers, religious hierarchies, holy symbols, and the practices of secret cults.
Smithing: Requires you to declare what you're specializing. Blacksmithing, weaponsmithing, armorsmithing for example.
Stewardship:
Tailoring: Allows you to make objects such as clothing out of woven materials.
Wisdom reflects how attuned you are to the world around you and represents perceptiveness and intuition.
Animal Handling: Measures your ability to control domesticated animals or intuit an animal’s intentions.
Agriculture:
Art: Determines your ability to create artwork such as a painting, sculpture, composing music (but not performing).
Insight: Determine the true intentions of a creature.
Medicine: Lets you try to stabilize a dying companion or diagnose an illness.
Perception: Lets you spot, hear, or otherwise detect the presence of something. It measures your general awareness of your surroundings and the keenness of your senses.
Survival: Follow tracks, hunt wild game, guide your group through frozen wastelands, identify signs that owlbears live nearby, predict the weather, or avoid quicksand and other natural hazards.
Charisma measures your ability to interact effectively with others. It includes such factors as confidence and eloquence, and it can represent a charming or commanding personality.
Deception: Whether you can convincingly hide the truth, either verbally or through your actions.
Intimidation: When you attempt to influence someone through overt threats, hostile actions, and physical violence.
Leadership:
Performance: How well you can delight an audience with music, dance, acting, storytelling, or some other form of entertainment.
Persuasion: When you attempt to influence someone or a group of people with tact, social graces, or good nature.