How safe is condom? can i finish inside here without any worries?

Condoms: These can be very effective in both preventing pregnancy and warding off stds, but nothing is 100%. There are breakages, leaking, etc. As a general rule, used appropriately there is a 90+% efficacy, good luck.

Condoms: Are not 100%, but then nothing else is either. If used properly and appropriately their effectiveness is usually estimated at 98%, but there is no way to know exactly. Some people use two condoms, others add in another contraceptive method at the same time to increase safety.

Nothing is certain: Condoms are effective birth control, but nothing is 100%. In particular, condoms sometimes break, & it is important to put it on before any genital-to-genital contact. It's much, much better than not using anything, & unlike most other birth control, it helps prevent sexually transmitted diseases (stds) too. If the failure possibility worries you, use a better method or don't have intercourse.