"Rebel" series bodies have no seals, gaskets, or o-rings on the body. They aren't weather resistant at all.
High end cameras like the 1D X, 7D / 7D II, tend to get the best weather sealing treatment. The 5D series bodies get weather seals too, but since the 5D isn't thought of as a sport camera and is less likely to be used in inclement weather the seals aren't as aggressive as they are in the 1D X & 7D bodies.
The mid-range bodies such as the 60D, 70D, & 80D also get weather seal treatment, but again... not quite as aggressive as, say, the 7D.
You can find videos of the 7D being heavily abused and they keep working. I would not subject a 70D or 80D to that level of abuse. The weather seals are not "water proof" and you should never dunk a camera in water (though I have heard of 7D's falling in water, being pulled out, dried off... maybe left for a day or two to air-out, and then tested to find they are working great.)
Only _some_ of Canon's L series lenses (actually it's probably "most" L series lenses) are weather sealed. If it isn't an "L" series lens (e.g. "EF 70-200mm f/2.8L IS USM II") then it isn't weather sealed at all (not even a tiny bit). You'll know if an L series lens is weather sealed because there will be a silicon gasket on the mount that seals against the camera's mounting flange. ALWAYS READ the documentation on the lens because some lenses require that you do something to "complete" the seal (e.g. some lenses will say that you have to attach a filter to the front to complete the seal. Other lenses are just sealed with or without a filter.)
The seals are designed to protect you from things like light rain, spray, dust, etc. (assuming you keep the lens on... no camera is "sealed" if you decide to switch lenses in the middle of a downpour.) They are not designed to protect you against a torrential downpour or being blasted with water under pressure (e.g. don't point a pressure washer at it and expect the seals to keep out water.) If your camera does get wet, towel it dry before removing the lens, etc.
Salt water is especially bad for a camera. Just occasionally someone takes their camera to the beach to photograph surfers, etc. they wade out in the water, get hit with a big wave (underwater) and most cameras will not deal with that well. If you KNEW that you needed to shoot around salt-water and there's a possibility of the camera going completely underwater (even if by accident) then you might want an underwater housing (which can be really expensive.)
If you know you are going to be shooting when it's likely to be exposed to water (e.g. it's expect to rain that day) then having a rain-sleeve for the camera is a good idea.