the translations are not always that literal, otherwise they end up sounding unnatural. '-weza' is 'be capable' and the phrase 'you can do it' is generally intended as 'you are capable', 'it' being arbitrary
Yeah, so I'm asking for the to-infinitive of the word. Sounds like that would be kuweza, right? So kuweza becomes ninaweza in 1. person singular, or wanaweza in the 3rd person plural as is the case here.