1-nga--ba nakhoCan I come in? — Ndingangena?We can go — SingahambaIt's easy to change a tyre; you can do it yourself — Kulula ukutshintsha ithayara; unakho ukulitshintsha ngokwakho
2-aziI can speak Sesotho — Ndiyakwazi ukuthetha isiSuthuJohn can swim but his little brother can't — UJohn uyakwazi ukuqubha kodwa ubhuti wakhe omncinane akakwazi
The opposite of 'can' is 'cannot'. It is unusual because you write it as one word.
1itotiinkonkxaBuy a can of beans — Thenga itoti yeembotyi