This is always a good first thing to do. Low voltage is a bad thing for modern cars that run almost entirely off of electrical components and computers and, by cleaning the battery terminals and cable clamps thoroughly, you remove resistance that usually brings the voltage back up to a better level for a while. That gives you time to test the battery and prepare for buying a new one if needed.
I had a 2005 Corvette that would not start because the voltage was not high enough to get the column lock (a common failure point) to disengage. Voltage on the ECU was 11 or so but at the terminals was 12.5 or so. Plenty to start the car but not enough to get the ECU to get the column lock to disengage. I started carrying around a wrench and battery terminal cleaner so I could disconnect it, clean the terminals and clamps, reconnect and BAM! Car fired up.
It's a cheap and easy thing to do first.