The preposition ke marks the destination or recipient, roughly equivalent to "towards", or "until [a time]". This is used to indicate motion towards an object, to show the destination of an object, the recipient of an object, or to specify the end of a time range.
mi le tun ke osa 18. - "I am busy until 18:00"
mi le lo ke insu mi. "I am going to my house"
mi le tene minuli ke tu in kuwosi. - "I gave a fruit to you"