'Ada' and 'Punya' can mean 'to have' but translate differently to english.
Eg:
Saya ada (sebuah) mobil. - I have a car. (ada)
Disana, ada sebuah mobil. - Over there, there is a car. (ada)
Saya mempunyai sebuah mobil. - I possess/own a car. (punya)
Saya punya mobil - That car belongs to me. (punya)
Mobil itu kepunyaan dia - That car is in his possession. (punya)
Do you have a car? - Kau ada (sebuah) mobil kah? (ada)
Do you own a car? - Kau ada (sebuah) mobil kah? or Adakah kau mempunyai sebuah mobil?
Is this your car?/ Do you own this car? - Adakah mobil ini engkau punya? Ya atau Tidak.
Just another addition. 'Punya' is used like the English possessive 's.
Eg:
This is Mary's car. - Ini Mary punya mobil.
Where is Ram's telephone? - Dimana Ram punya telepon?
Who took Anthony's pen? - Siapa mengambil Anthony punya pen?
I like Tara's hair. - Saya suka Tara punya rambut.