I got 2 messages popping up, one says turn right side signal, and the other says check coolant level, check the coolant level ans its normal, could it mean it time to flush it ?

The sensor only monitors the level of the coolant, it does not monitor the condition of the coolant. It's more likely you have a faulty coolant level sensor or low coolant level. Have a technician check the level, even if it looks good to you. Mercedes engines have extended life coolant that doesn't need to be flushed until 100,000 miles

The other message means you have a bulb out for your right side turn signal.