Being Frugal is when you try to spend as little money as possible and save money.
For example when you buy cheaper foods or grow your own food instead of spending money to buy that food or spend very little money to buy the food then you're being frugal.
Or when you refuse to upgrade your clothing for newer clothes until they wear out completely then that would be an example of being frugal.
Another example of being frugal is you live in a modest house and not a bigger fancier house even when you can afford to.
Or you drive an older car and continue driving the older car until it no longer runs or gets too expensive to operate.
Being frugal means to live simply and live below your means.