“Actually it's been kind of slow this week.”

You're talking with someone you know who works in another part of your company. She asks if you've been busy lately. You're not busy, so you say:

Actually it's been kind of slow this week.

actually

Use this to tell people something that's different from what they are expecting to hear:

Wow, this is actually pretty good.

Actually, I'm looking to switch careers.

(something) has been (adjective)

Use "has been___" or "have been ___" when you're describing a situation that started at some time in the past and is still continuing now:

Sales have been pretty good.

It's especially common to use "has been ___" with "this week", "today", "this year", or other phrases that indicate the current time period:

I've been worried about this all day.

it's slow

Describing a situation as "slow" means that it's not busy:

It's really slow today.

We've had a really slow month.