Hey there!
N₂ + H₂ → NH₃
Balance N.
2 on the left, 1 on the right. Add a coefficient of 2 in front of NH₃.
N₂ + H₂ → 2NH₃
Balance H.
2 on the left, 6 on the right. Add a coefficient of 3 in front of H₂.
N₂ + 3H₂ → 2NH₃
This is our final balanced equation:
N₂ + 3H₂ → 2NH₃
Hope this helps!