Something

[itsme7]

what does it mean when we see a person and our heart stars beating?

[Atheist]

It means you fancy me. :-)

[Buenchico]

It means that the "fight or flight" reaction has been triggered.

That could, for example, be because the person you've just seen has previously threatened to kill you.

It could also be because the presence of that person causes you anxiety (e.g. if you see your boss walk in when you're spending your time on social media, rather than on his spreadsheets).

Equally, it could be because you're in love with the person (or, at least, starting to feel that way):
https://orthology.com/what-happens-to-your-heart-when-you-fall-in-love/

[Prudie]

Or you're absolutely penniless and it's the postman with bills.

[Buenchico]

^^^ Been there, done that, Prudie ;-)

[sanmac]

A doctor or nurse has put the paddles on your chest.

[Captain2]

My heart beats all the time - I think I'm normal??!!

[Ellipsis]

It means their defibrillator worked ...

[Prudie]

I was also speaking from experience Chris!

[sandra4444]

I worry about the one i see after it stops.

[bobbinwales]

Lol Sandra. ( That proves to me your not gulliver... you have a sense of humour but don't suffer from pmsl disorder

[nailit]

//what does it mean when we see a person and our heart stars beating//
Speaking from experience, its usually because said person has handcuffs and is dressed in Her Majesty's Police uniform.

[Canary42]

[Tilly2]

You like, or possibly, love them.

[Old_Geezer]

You mean it hadn't been beating previously ? Are you sure that you aren't a vampire ?