Backgrounds can be extremely varied from person to person, even those that come from similar backgrounds still have different abilities. For example, two criminals can be wildly different, maybe one is good at intimidating people to repay loans, and the other one is good at lockpicking safes.
To reflect this, you have 2 background points to spend on additional abilities for your character. You may only take each option once.
Varied. You get 1 skill proficiency or 1 tool proficiency. Additionally, you also get 1 language proficiency or 1 instrument proficiency.
Skilled. You either can take 2 skill or tool proficiencies, or you can gain expertise in one skill or tool of your choice. You must already have proficiency in the skill to gain expertise in it.
Linguist. You get 2 languages and two instrument proficiencies
Feat. You may take a feat. If the feat increases an ability score, you cannot increase it above 20 using this feature.
Ability Score Improvement. You may increase one ability by 2, and another one by 1. You cannot increase an ability score above 20 using this feature.