How kind of climate the Earth would have if instead of rotating in an inclined?

Vertical to what?

The further the equator is from the orbital plane, the greater the difference in the seasons.

If the Earth's axis was not tilted, we would have no seasons. The tropics would become uninhabitable from the heat, the weather would be very turbulent, and the length of the day and night would not change over the year.

If it happened suddenly, most life on Earth would die out.

Much larger differences in seasons I think

i like your english.