Why does my car not start at times,batteries good,brake light, and ABS light on? on 2000 Ford Focus

Battery is good, doesn't sound like the starter, brake light is on and so is the
ABS light. Turns on when it wants to, please help. I was suggested to change the terminals???

Asked by for the 2000 Ford Focus
Really need to have a good auto electrical person test the starting and charging system to see what is defective, guessing is usually futile and can get expensive.
Thank you, but first Im going to change and clean the terminals. That seems to be the problem