How do I get my players to roleplay more?

Whenever we play, my players are very into initiative (albeit their attacks and moves are really repetitive), but they don't communicate very well with each other or with NPCs. This is their first game though, so it's understandable.

It gets annoying, though, when we are out of initiative and they need to solve problems and communicate and so forth. I describe something, and afterwards they'll sit there in silence. I sometimes have to resort to asking them "what do you do?" until they do something.

How do I introduce roleplaying to them in a situation where it is not super intense or important?

I would try to lead by example through NPC interaction. Ask them questions as an NPC and regard what they say is being said "in game". Using this, they end up role-playing to an extent overtime they talk, and it helps tell them that they can affect the world they are playing in by actually communicating with those that are in it.

If they are in a place where an NPC in not readily available or implied to exist, a good old-fashioned vengeful ghost or spirit of a recently slain enemy threatening to exact revenge or asking for a dying wish will work. It creates a situation were communication is immediately needed and simple questions/answers are all that is needed to avoid getting possessed or whatever.

The key here is to sell it as the GM when you're an NPC. Newer players tend to be withdrawn a bit because they're not sure what to do and often a little embarrassed to fully embrace the idea RP. IF you do it, they will do it, little by little over time. Hope this helps!