When there is a current in a resistor, energy is transferred to heat it. This heating effect is useful in some situations and a problem in others.
It is an advantage when heat is the purpose of the device. Kettles, toasters, electric heaters and ovens all use a wire with a high resistance that gets hot. In a filament lamp the thin wire becomes hot enough to give out light. In a fuse a thin wire melts when the current is too high, which breaks the circuit and protects it.
It is a disadvantage when the heat is not wanted. Energy is wasted as thermal energy in wires and in devices such as phone chargers and computers, so they are less efficient. Components can overheat and be damaged, wire insulation can melt, and a fire can start. Computers need fans and heat sinks to carry the heat away.