a bit (adjective)

"A bit" is similar to "a little", "kind of" or "somewhat". It's used when you want to lessen the degree of a description:

He's a bit shorter than me.

He has a video of me from when we were in college that's a bit embarrassing.

"A bit" is used for adjectives that are negative. So you wouldn't say that an event was "a bit fun" or that a person is "a bit nice". But you can say that the event was "a bit boring" and the person is "a bit rude".

"A bit" is slightly formal. It's more formal than "kind of" or "a little", but more casual than "somewhat":

kind of > a little > a bit > somewhat

come across as (something)

The way that you "come across" to people is how they see you and think about you. This phrase is a way to explain what people think of you, which can be different from how you think of yourself. So although you may think of yourself as cool and sophisticated, you might come across as unfriendly instead.

You can follow "come across as" with a noun phrase that describes a person:

He came across as a really friendly and sweet guy at first.

Or you can follow it with an adjective phrase that describes someone's personality, like in the example above. Here's another example:

Do you think I come across to people as kind of boring?

But it sounds strange to just have a single-word adjective after "come across as", like "come across as boring" or "come across as needy".

I do think (sentence)

This is a way to express your opinions delicately, when you think that someone might disagree with you:

A: I'm just going to do it myself.

B: Hmm... I do think it might be a good idea to call a professional and at least get an estimate.

When you say this, the stress is on the word "do".

(someone) is aggressive

Someone who is "aggressive" is forceful and quick to attack. "Aggressive" behavior threatens people:

Man, he's so aggressive all the time. He needs to just chill out.

You can talk about animals as being "aggressive":

You can pet her. She's not aggressive.

Being "aggressive" is usually bad, but in certain situations, the word "aggressive" can have positive associations, like in sports or in sales:

You've got to be aggressive and go for the win.