Questions & Answers about Мы не хотим говорить о них.
Why is the word for 'them' них instead of их?
After the preposition о (about), we must use the prepositional case. The base prepositional form of они (they) is их. However, in Russian, whenever a third-person pronoun (he, she, it, they) comes directly after a preposition, an extra н- is added to the beginning. So, it becomes о них.
Why do we use о here instead of об?
You use о before words that start with a consonant sound, like них. You switch to об before words that start with a vowel, simply to make it flow better when speaking (for example, об этом - about this).
I remember 'to want' having a 'ч' sound, like in я хочу. Why does хотим have a 'т'?
The verb хотеть (to want) has an unusual pattern. In the singular forms (I, you, he/she), the stem changes to ч (like я хочу, он хочет). But in the plural forms (we, you, they), it keeps the т from its dictionary form: мы хотим, вы хотите, они хотят.
Why doesn't говорить (to talk) change its ending to match 'we'?
Because the first verb (хотим) is already conjugated to match the subject (мы). When you have two verbs together like 'want to talk', the second verb stays in its infinitive (dictionary) form, exactly like in English.