When you level up, you'll be rewarded points you can spend on Attributes and Trade Skills. You can spend these points however you see fit. There are no classes in New World: Aeternum.
Attributes are an expression of your character's overall capabilities as a person. They determine things like your total HP and Stamina, your defense against various types of damage, and whether or not you can wield certain weapons. You can hover your mouse over each attribute to learn about its affects, and you can experiment with your points to see their effects before committing to them.
Trade Skills represent your ability to perform different actions. This includes harvesting, refining, and crafting items. You can see the specific effects of each level of a trade skill by mousing over the number for any given level.
You won't be able to unlock every point in every skill. You'll need to work with other players or use the <a action="GoToPage" data="TradingPost_Overview">Trading Post</a> to obtain high tier equipment.