We use can + infinitive without to.
We don’t add -s after he/she/it. We use can for all persons.
Can is an auxiliary verb and has a negative and interrogative form. We don’t use do/don’t to make questions and negatives.
We use can/can’t to talk about ability in the present (=things that we know how to do).
We use can/can’t to ask for permission or to say if something is possible or not.
We use can/can’t to ask for something and to order in bars, restaurants, shops, etc.