''C'est'' is what we call a présentatif in French grammar. Why? Because it grammatically introduces présente more often than not something or someone.
The French phrases ''c’est'' and ''il/elle est'' can be tricky because they are close grammatically but not interchangeable. * Which one to use depends less on meaning than it does on grammar.
For example…
J’aime ce tableau. Il est joli. I like this picture, it’s pretty.
C’est un joli tableau. It’s a pretty picture.
Another important thing to remember is that "c'est" is neuter, which means it takes the masculine for by default. Assuming you're referring to something feminine but you decide to use it to convey generality.
I.g. Wow, c'est beau ! - Wow, it's beautiful! What is beautiful? Could be the river (which is feminine in FR), could be the lake (which is masculine in FR), but it isn't specified, so we use "c'" and therefore keeps its default masculine form.
If we modify the the action by a different verb, this can also happen, these context are colloquial however:
EX.
-As-tu rangé ta chambre ? (Did you clean your room?)
-Oui, maman, c'est fait ! (Yes, mom, it's done!)
Here we're not using the same verb, therefore the subject is elided, and can be replaced by "c'" instead of the more proper way keeping the action verb intact.
EX.
-As-tu rangé ta chambre ? (Did you clean your room?)
-Oui, maman, elle est rangé/je l'ai rangéE (Yes, mom, it is cleaned/I cleaned it)
Common trick for some cases: if it's followed by a determiner it's usually "c'est" if it's followed by an adjective, more often than not, it's "il/elle est"
C’est + determiner + noun (with or without an adjective)
C’est le docteur. That’s the doctor.
C’est ma jeune sœur. She’s my younger sister.
Ce sont nos voisins. Those are our neighbors.
Ce sont des amis intimes. They’re close friends.
Il est + adjective:
Il est sympa. He’s nice.
Elle est intelligente. She’s smart.
Ils sont sages. They are wise.
Elles sont belles. They are beautiful.
Here's a good website on the difference to further your understanding, if needed: https://www.lawlessfrench.com/grammar/cest-vs-il-est/