Look at these sentences:
Il fait beau.The weather is nice.
Il fait mauvaisThe weather is bad
Il fait froidIt is cold (outside)
Il fait chaudIt is hot (outside)
Il fait bon.The weather is nice.
Notice that to talk about the weather in French, you will use the fixed expression
Il fait + [adjective]
(In this case, it literally means "it makes/does...")
You would never say Le temps fait bon.
You cannot say C'est chaud about the weather, but you can about something you touch or taste (like a cup of tea).
Nuance between il fait beau and il fait bon:
Il fait beau expresses that the weather looks nice (blue sky, sunny...)
whereas Il fait bon is more about how the weather is / feels (the temperature), meaning not too hot nor too cold: "It is warm".
Case of il fait du soleil or il fait soleil:
This seems to be presented as idiomatic in a lot of French courses, and to be perfectly honest, some French people use it. However, it is not good French and still sounds clunky and child-like to many French ears (including mine).
Il fait should always be followed by an adjective, and il y a by a noun.
See also Talking about the weather in French - il y a + [nom]
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