How do I replace cabin air filter in suzuki aerio 2002, I understand I need to remove the glove box but how do I do that exactly? do I need any tools? which tools?

https://www.youtube.com/watch?v=KFbfjNH19E8
is this a video you have seen

Usually the cabin air filter is located under the dash, under the glove compartment.

If you are talking about the cabin air filter, this filters the outside air for the HVAC.
Hastings Filter (#AF1057) shows one for the 97-03 MY trucks.

Remove the screws that hold the horizontal filter housing cover from behind the glove box (no need to open the glove box);

Pull the cabin filter straight down (sits vertical behind the glove box inside the housing).

Install replacement and reattach the cover.

the cabin filter is behind glove box, open glove box an release it so it opens farther to get to filter ( should be release clips at sides of glove box)

The cabin filter is located behind the glovebox.
First lower and remove the glovebox
If it has not been changed before, you will need to cut the plastic crossbrace behind the glovebox.
Once out of the way, unbolt the steel reinforcing frame behind the plastic and set it aside.
The cabin filter is mounted vertically behind it.
See images for further explanation:

To change the cabin air filter one needs to remove the glove box first. This is reasonably simple and involves a couple of screws, the rubber glove box limit pads, and a 10mm nut. The air filter is located in the heater assembly directly behind the glove box. The filter is removed by releasing the plastic clip holding the filter and withdrawing the filter forwards. (The filter is installed like a vertical drawer.). The Hyundai web site (www.hmaservice.com) has a good description.
For a 2002, you simply slip the black ring off of the glove box clip on the right, and pull the left side of the glove box in slightly so the rubber glove box limit pad will clear it's channel. That allows the glove box to open forward and gives access to the heater assembly directly behind the glove box. The air filter holder is held in place by four plastic clips that you squeeze together in pairs to release the holder. Pull it out like a drawer. Remove the old filter by squeezing the top and bottom (or front and back, depending on how you hold it) of the filter together. This will bow the white plastic sides of the filter so that they clear the four small, black plastic protrusions from the sides of the holder that keep the filter in place. Reverse the process with the new filter and you are done. Takes about 10 minutes.

The cabin air filter is located behind the glove box, you will have to remove the glove box, behind the glove box is a cover about 1" high and 7" long, remove that cover and you will see a tray that holds the cabin air filter, remove the tray and you can replace the paper cabin air filter, I recomend using a Toyota cabin air filter, the Toyota cabin air filter is a HEPA air filter and is available at any Toyota dealer for about $ 30

Remove all of the contents in the glove box. Remove the glove box door support. Open the glove box. Squeeze the sides of the glove box inward, to drop the box door open further. The cabin air filter is in a small rectangular box, behind the glove box.

Toyota initiated cabin air filters in Corollas starting in 2003.

good news is it can be changed with no tools in about 2 minutes. just take out the glove box and the cover comes off easy.