All kinds of experiences and training can shape your character beyond what you learn by advancing in your class. Abilities that require a degree of training but can be learned by anyone—not only members of certain ancestries or classes—are called general feats.
For most classes, you gain a general feat when you reach 3rd level and every 4 levels thereafter. Each time you gain a general feat, you can select any feat with the general trait whose prerequisites you satisfy.
General feats also include a subcategory of skill feats, which expand on what you can accomplish via skills. These feats also have the skill trait. Most characters gain skill feats at 2nd level and every 2 levels thereafter. When you gain a skill feat, you must select a general feat with the skill trait; you can’t select a general feat that lacks the skill trait. The level of a skill feat is typically the minimum level at which a character could meet its proficiency prerequisite.