Keep calm and carry on!

Keep calm and carry on!
Have” refers to owning something and “got” refers to receiving something.
Nouns can be countable or uncountable. Countable nouns can be counted, e.g. an apple, two apples. Uncountable nouns cannot be counted, e.g. air, rice.
Verb tenses in English are used to indicate the time at which an action takes place.