tu capisci?
that means DO YOU UNDERSTAND, it is an -ISC verb so the endings changed when it is conjugated although the verb "to understand" is capire
Capito or Capisco
capisci
Do you understand as a direct translation is "capisci?" If you are asking if they understood, it's "hai capito?" but generally in spoken Italian you would leave out the hai and just say "capito?"...
Non capisco
Capire is an Italian equivalent of 'to understand'. It's the infinitive form of the verb. It's pronounced 'kah-PEE-ray'.