How to make a conversation with the guy if you're a boring person with not to talk about?

there's a guy at my workplace that I only say hi and bye and even when we are together, we never have any conversation. Then one day he suddenly asks me about my favorite to go drink at Starbucks and buy me the drink the next day. And he then starts asking me about my favorite food and stuffs and offer to get me the things i likes.

I am interested in him; however I dont know if he's being nice or do actually like me too?
Also he doesn’t talk to me if we in the room with other people, and it is so awkward that i dont know if should approach to make a conversation with him. What would be a best way to start conversation and what would i talk about. Please help

How to make a conversation with the guy if you're a boring person with not to talk about?
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