Hrodna is in far western Belarus, about 280 km from Minsk. Direct trains run from Minsk several times daily; the journey takes four to five hours on the faster services. There are also direct trains to Warsaw and Vilnius, which makes Hrodna a natural entry point from Poland or Lithuania — and potentially a first stop on a westward journey out of Belarus.
The border crossing at Bruzgi/Kuźnica Białostocka to Poland is about 15 km away; the crossing at Šalčininkai to Lithuania is roughly 70 km north. Both require a valid Belarusian visa unless you qualify for visa-free entry (check current rules — Belarus has periodically offered visa-free entry to some nationalities at certain airports, but the border crossing situation changes). The train from Warsaw to Minsk passes through Hrodna and can be a scenic way to arrive.
Bus connections run from Minsk, Brest, Vilnius, and Warsaw. The bus station is near the city centre.