Here is a quick start:
uniforms = values provided by application or engine (like Leadwerks), this usually what makes other shaders hard to use in Leadwerks since the naming here can be anything, everyone uses their own convension.
out = usually output from the vertex shader for input in fragment shader
in = input, usually from the vertex shader
cameramatrix = viewmatrix in other shader references
camerainversematrix = inverseviewmatrix in other references.
projectioncameramatrix = viewprojectionmatrix, MVP, has several names used around.