Why are the letters T flikering?

I am so new to Blender its not even funny but I have managed to follow a tutorial and create this but I would like to know why the letters T are flikering like they are?
Is it because of the file format?

Thank you for reading

Check your model. It’s quite likely you have more than one set of faces forming the front of the T – coincident faces. One way to remove them is to select all the vertices on the face of the T and use Remove Doubles.

Apart from that I have often had issues with converting Text to mesh. The mesh is often messy. Remesh could help too.