Breakdown of Он мешает коллегам своими правилами.
он
he / it (for a masculine noun) / it (for a neuter noun)
правило
rule
коллега
colleague
свой
one's own
Questions & Answers about Он мешает коллегам своими правилами.
Why do we use своими here instead of его?
Свой is a reflexive possessive pronoun that refers back to the subject of the sentence (он). If you used его правилами, it would mean he is bothering them with someone else's (another man's) rules.
What case is своими правилами in, and why?
They are in the Instrumental case, plural. The Instrumental case is used here to show the means or instrument by which an action is done. He bothers his colleagues by means of his rules.
Why is коллегам in the Dative case instead of the Accusative?
The verb мешать (to bother, to hinder, to interfere with) requires its object to be in the Dative case. You don't bother a direct object in Russian; you create a hindrance to someone. Therefore, коллеги becomes коллегам.
I remember мешать meaning "to stir" or "to mix". Is this the same verb?
Yes, it's the exact same verb! Мешать means "to bother" when it takes a Dative object (like коллегам). It means "to stir" or "to mix" when it takes an Accusative direct object, like stirring soup (мешать суп).