What does it mean for a tangent bundle to be parallel?

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I am looking at page 8 of the paper here, just below definition 2.13. I have never come across a phrase such as '$T\mathfrak{C}\subset{TM}$ is parallel' - what does it mean for a tangent bundle to be parallel? If someone could also please explain the concept of 'trivialising' a vector bundle (a couple of lines below, regarding the pullback bundle $c^*E\rightarrow(a,b)$), it would be much appreciated. I don't think these questions require any knowledge of the paper, except perhaps definition 2.12 for the concept of 'trivialising'. Thanks!