What is the purpose of using vague language, according to the video?

To sound more natural and avoid being overly precise.

The video mentions using 'thingy' to refer to something. Explain when it's appropriate to use 'thingy'.

It's appropriate to use 'thingy' when you don't remember the name of something or want to be vague.

'A ballpark figure' means a rough estimate. You would use it when guessing a large amount or number.

A 'guesstimate' is a combination of 'guess' and 'estimate'. Some people dislike it, but the video doesn't specify why.

Around, about, more or less, give or take, or so, or thereabouts.

I can use vague language appropriately to sound more natural in English conversation.

1
When you don't remember the name of something, you can call it a thingy, or if you want to talk about a part of something, you can call it a bit.
2
To guess a huge amount, use the term a ballpark figure, and to give an approximate number, you can use expressions like around, about, or more or less.
3
To be imprecise with adjectives, you can use words like kind of or sort of, or add -ish to the end of the adjective.