"Does it mean its going to get flat?"
What? Seriously? Of course it is going down and NO it can't be repaired you need a new one. You will have to take the wheel off the car and take it to be replaced, it can not be driven on.
You'll need a new tyre. If you drive it with the flat you'll probably need a new wheel as well. Fit the spare to get to the tyre dealer
Assuming they stabbed it in the sidewall it can NOT be fixed. It can't be patched becausae it must flex. It is haeart-breaking to lose good tires because of idiots.
By the time you read this, it is probably not safe to drive on it. Change the tyre for the spare you should have (or use the car maker approved repair kit), then go to the garage/mechanic and show both.
If it isn't flat now it probably will be before you get to the shop.
It will only be flat on the bottom.
for the most part, the tread area can be repaired but the side wall is not.
Sidewall tire damage cannot be repaired.
You are too late
My nephew was playing around and he stabbed one of my tire with a knife once and it instantly started going having a small whoshing sound.It just happed less than 20 min ago .Does it mean its going to get flat? I can take to the shop right now so how long does it take to get flat?