"When the light will be turned on I will read well"
Translation:Taa itakapowashwa nitasoma vizuri
I don't know what lesson this is in, but the -po- is the relative marker for class 16 locative. It can either be "where" or "when", but I think usually "when". I don't mean in the sense of asking a question but in other kinds of questions. Eg.
ninapokula = when/where I eat
You can clarify which one you mean ...
wakati ninapokula = ((at) the time) when I eat
mahali ninapokula ((in) the place) where I eat
The relative markers can only be added to certain verb structures. One funny little quirk is that the future marker -ta- becomes -taka- when there's a relative marker after it. So the verb above breaks down as
i- = it (class 9)
-taka- = will (future before relative)
-po- = when/where (class 16 relative)
-wash(a) = turn on
-w(a) = be ...-ed (passive)