Honda Innova 125 cc: Every how many kilometers must I change its oil and its sparkplug?

I have bought a used honda innova 125 cc model 2003 with 13.300 kilometers.

Added (1). What kind of oil must I use?

Frequent oil changes are wise as it delays wear. Use fully synthetic and it will last even longer. Phone a Honda bike dealer and ask if you haven't got the owner's manual.

Every 10K or when needed.

Motorcycles are a harsher environment than cars. I would say every 6 months or 3,000 km, whichever comes first. Also keep checking the oil level and add as necessary. Many mc mfrs suggest changing the plug every 12 months. Don't forget the oil and air filters, too. Go online and see if you can download the owners manual, then do what it says.