If your coolant is just a little bit low then it can be safe to drive with the low engine coolant.
However watch your temperature gauge on the dash and if it gets too hot then pull over and allow the engine too cool down.
It's best though to keep your coolant level full and keep a couple jugs of engine coolant in your toolbox or in the trunk of your car.
I keep 8 Jugs of coolant in my car trunk and 8 jugs of coolant in my trucks toolbox just in case I need the coolant.
Usually I only have to use half a jug of coolant but I have the coolant there in case I get a major coolant leak and also have radiator hoses, heater hoses etc especially when on a long road trip.
Driving with low coolant can lead to the engine overheating which can then lead to blown head gasket and warped engine heads.
That can mean an expensive repair bill.
So it would be better to add some coolant.
Loosing a little bit of coolant is normal after driving a lot and I loose around 1/2 gallon of coolant in 5000 miles of driving especially in the summertime.
I just make sure to top off my coolant and check over the coolant system to ensure it's working properly and in good condition.
After 10 years my radiator hoses, water pump and heater hoses all get replaced with new ones just for peace of mind.