Resistance decreases if the cross-sectional area is increased. This sometimes confuses people, as it's not obvious. Look at these two pieces of metal:
The narrow wire has fewer paths available for the electrons to move through. Whilst the larger wire has many more routes they could take. This makes conduction easier.
Think of the fat wire as being a 6-lane motorway. There is always somewhere to go, so going quickly is easy. The thin wire is like a narrow countryside lane. Movement is restricted, so you have to drive slowly!