“There's this nosy lady next door who's always in our business.”

You have a neighbor who always wants to know about you. She often looks into your yard to see what you're doing. You're describing this situation to some people at a party. You say:

There's this nosy lady next door who's always in our business.

this (person/thing)

In casual conversation, you use "this" instead of "a" when you want to start telling a story about something. Using "this ___" suggests that you're going to say something else about the subject.

For example:

I've had this song stuck in my head for two days!

If someone says this, they're probably going to continue by saying the name of the song, or singing part of it.

(someone) is nosy

A "nosy" person is someone who wants to know private information about other people. It has a negative association, because "nosy" people are annoying.

People that are often "nosy" include neighbors and family members.

(someone) next door

A person who's "next door" lives in the house or apartment right next to yours.

Have you met the guy next door?

(someone) is in (someone's) business

Being "in someone's business" means getting involved in their personal lives.

For example, if you've tried to learn or give advice about a person's:

• finances
• love life
• health issues

...then you're "in their business".

This is why, when someone is getting too personal, you say:

Get out of my business!