Que without accent is a nexus. A link that connect tow sentences in spanish.
Yo quiero
que hables español
Yo (sujeto) quiero(verbo) que (nexus) Tú( 2o sujeto) (2o verbo) hables (complemento) español
There are two types of sentences in spanish: The simple sentence
subject+conjugated verb+complement or the double sentence
subject+cojugated verb+complement+nexus+2nd subject+2nd cojugated
verb+complement
And
Qué is just used for questions