When somebody wants to say that:
then you use “can” followed by the infinitive. The negative form is cannot or can’t.
An alternative is to use “is able to” – but can is more commonly used.
The past tense of can is could. It is often used with the 5 senses (see, hear, smell, taste and feel as well as with remember and understand).
Could is also used when explaining a general ability.
Using could and was able to, managed.
Could is used to explain a general ability.
Was able to is used to explain that somebody did something in a specific situation.