Lesson
White to move. Main line: 1. Rf7 Bd4 2. Kg3 Bg7
The bishop stays close to its king and simply refuses to be separated from it. There is no way to attack both at once, and the extra material never converts into a threat.
The defender does need to avoid one thing: being driven into the corner the bishop does not control, where mating nets exist. Keeping the king near the safe corner is the whole defensive idea.
The tablebase confirms the draw, and every move in the line above was checked to keep it. Recognising drawn material balances is a practical skill in its own right — it decides whether to trade into this ending or to avoid it.