You will gain a number of Skill Points as you create and level up your character. When you invest a skill point into a skill, that skill gains a +1 bonus. You can invest a maximum of 10 skill points into one skill.
You can also invest skill points into a Tool instead, to a maximum of 10.
Since Tools query a skill, you can have a maximum skill point bonus of 20 from a tool skill check. This doesn't include external bonuses you may receive.