In English, existence is usually connected with the verb "to be".
- I am a human.
- This is a pen.
- The sky is blue.
- Four plus three is seven.
The first sentence can be understood to say "I exist as a human", and simply speaking, this is probably true. The fourth sentence is more difficult to understand, because it can be understood to say "seven exists as the sum of four and three", but "seven" is not something that we can see or touch like a pen or a human.
Existence Facts for Kids. Kiddle Encyclopedia.