Pretty easy stuff if you now the make and model… information that is needed to make any repairs or adjustments… and no one can say for sure what you want to know without having the make and model…
I gave it for Atwood and here it is for Suburban…
SW6P P= pilot SW6PR = pilot with reignitor SW6PE= combination pilot and electric SW6PER= combination pilot and electric with reignitor SW6D=direct spark ignition SW6DE=direct spark ignition and electric
Some RV manufacturers do not install interior switches for the water heater. Then, as Old Bicuit said, the two water heater brands have switches right on the water heater itself. A very simple way to determine if yours is electric is to look at the circuit breakers and see if there is one marked Water Heater.
If it's a Suburban Brand... In outside compartment there will be an ON/OFF switch in corner and there will be 2 reset buttons on rubber cover. The electric element will be under a cover behind gas valve
If it's an Atwood Brand.... Control panel will have 2 switches Electric element will be on backside (inside RV) under a cover
Doesn't the data sheet in cabinet/drawer list the various appliances etc.?
If your trailer has a 'systems control panel' and the water heater is gas and electric, there will be two switches for the water heater. One is for the ignition for gas operation, the other to turn on the 110v heating element for electric operation.
Typically, you will have a switch with your master switches that says electric. That is where mine is on my Laredo. You will also have an on/off switch inside the outside cover of the water heater. This switch has to be on before you turn on the inside switch.