Quanto costa is an Italian equivalent of 'How much is this'. In the word by word translation, the interrogative 'quanto' means 'how much'. The verb 'costa' means '[he/she/it] costs, does cost, is...
[Io] non parlo molto italiano is an Italian equivalent of 'I don't speak much Italian'. In the word by word translation, the subject pronoun 'io' means 'I'. It doesn't have to be used in the...