"Aamir can sleep."

Translation: आमिर सो सकता है।

[SuperFlorus]

Why not sona sakta hai?

[Zerenei]

When you use the verb सकना in Hindi, the verb that comes before it is only in root form, not in the infinitive. It's the same way in English! We say "Aamir can sleep," not "Aamir can to sleep."