Learn Polish: Ta nowa wizja to coś genialnego. - This new vision is something brilliant.

This is a special rule for indefinite pronouns like coś (something), nic (nothing), and cokolwiek (anything). When you add an adjective to describe them, that adjective must take the neuter singular Genitive form. You can think of it as literally saying "something of brilliant".

Why is to used here instead of jest for "is"?

In Polish, to is often used as a linking word to equate two things ("A is B"). When you use to, the noun phrase that follows it stays in the Nominative case (here, the pronoun coś is Nominative). If you wanted to use the verb jest, the following phrase would need to be in the Instrumental case: Ta nowa wizja jest czymś genialnym. Using to is very natural and common for equating two concepts.

If to is followed by the Nominative case, why does genialnego have a Genitive ending?

The word coś actually is in the Nominative case here, which perfectly satisfies the rule for the to copula. The word genialnego is Genitive only because it is modifying coś. The entire phrase coś genialnego acts as a single, Nominative block in the sentence overall.

Is genialny a false friend? It looks exactly like the English word "genial".