"He is Bruno."
"il/elle est" and "ils/elles sont" change to "c'est" and "ce sont" before a modified noun, that is, a noun preceded by a modifier. A modifier can be:
- an article: un, une, des, le, la, l', les
- a number: un, deux...
- a possessive adjective: mon, ton, son, ma, ta, sa, notre, votre, leur, mes, tes, ses, nos, vos, leurs
- a demonstrative adjective: ce, cet, cette, ces
The rule also applies to names - you can't say "Elle est Anne" or "Il est Bruno", you use "C'est Anne" and "C'est Bruno".
These articles go into more detail and are worth a read.
Also, the Tips and Notes for the Gallicism skill (click the lightbulb icon when you open the skill) give more information.
The example language instruction seems to very specifically give examples that all have a determiner article so it was not at all clear that when you are naming someone by name (not by a descripter) and so there is no le/la/des article with it -- that you are supposed to replace Il or Elle with Ce. I think names need to be specifically given as an example because that is so different from English.
From the Tips and Notes: C'est or Il Est? "When describing people and things with a noun after être in French, you usually can't use the personal subject pronoun like il, elle, ils, and elles. Instead, you must use the impersonal pronoun ce, which can also mean "this" or "that". Note that ce is invariable, so it can never be ces sont."
A name is a noun.
They go on to mention that professions are an exception that can use "il or elle. "Il est medecin."
I agree that it would be good to have an example of a personal name used with "C'est"
The dictionary hint for "He" on the original page specifies "c' " for the translation, but people by now might not check.