1998 Nissa Sentra brake light & battery light come on

check the globes as filament for tail light it could be blown
while the filament for the brake light usually in the same globe
could be ok

check fuse 36 tail light fuse may be under bonnet in relay box
check relay for tail light
is relay switch getting 12v from the cpu device that controls tail light
check on relay pin tabs

Question edited for clarity.
Question moved to model category.

'95-'99 Nissan Sentra Fuse Box Diagram

https://knigaproavto.ru > shemy > 720-1995-1999-nissa...

Oct 27, 2018 - Fuse Panel Diagram Nissan Sentra Base, XE, GXE, SE and GLE (B14; 1995, 1996, 1997, 1998, 1999)

check if the alternator is charging

Worn out battery--check that out

Did you not check for codes yet?

OK, the brake light is caused most likely by the emergency brake cable being broken, and the pedal or brake lever is not in position.

Also, the brake light could be caused by low brake fluid level. Check that, too.

Battery light, is caused by the charging system not working, like a bad alternator or shorted out battery, or both.

I would have these issues repaired before driving any distance.

good day Sir, try to check the alternator and the voltage regulator hope this tips will help you.

Brake lights that won't turn off with a good switch need this.
[46512] STOPPER-RUBBER on the brake pedal bracket to contact the switch.
http://www.courtesyparts.com/frontier-parts-d22u-1998-2004/genuine-nissan-parts/brake/465-brake-clutch-pedal/-c-2129_2130_2232_2238.html

You could have faulty altenator or short causing the battery to drain. The engine light usually comes on when anything electrical or sensor wise is faulty. Brake light will come on if, low brake fluid, e-brake handle is up.

Have you checked the alternator?

your brake light switch is stuck its above the brake pedal