Yes a credit score of 770 is a good credit score.
A 770 credit score is not an excellent credit score but a 770 credit score is still considered to be a good credit score which means that you can usually easily get approved for credit cards, auto loans, mortgage etc.
The higher your credit score the better chance you have at getting approved for loans, credit cards, mortgages etc.
The lower your credit score the less chance you have at getting approved for those things.
Credit scores range from a low of 580 and lower to a high of 800 and above.
When you have a credit score of between 580 to 559 which is considered to be a fair credit score, a good credit score is between 670 to 739 and a credit score of between 740 to 799 is considered a great credit score.
A credit score of 800 and above is considered excellent and you can easily get approved for credit cards, loans, mortgages etc.