Que, quien, lo que
What are the differences in when to use que, quien and lo que'
Te digo que él es quien sabe lo que está pasando.
That's one example.
Punisher is right: "lo que" translates literally as "the (thing) that" (lo = the thing, que = that), normally translated as "what". "Quien" is "who", but there are quite a few rules regarding its use; it is not always like in English (e.g. as a relative, it cannot be the subject of a subordinate clause). "Que" has many many different uses; it is translated as "that", "who" and "which". Giving all the details would be a long email, I'm afraid.
Please write the sentences you have problems with. Puni is right , we need context , as usual.
you can try and look for the words in the dictionary, or you will have to wait for one of the native speakers to show up and for sure you will be asked to come back with context. but regarding Lo que:
ill try to give an example and hope not to be mistaken---|-> Lo que hay en mi mano es un libro.
what is in my hand is a book.
help me please!