How long are days and years for each planet in our solar system?

They cover quite a range! While the year is determined by the orbit, and therefore increases as you get further from the Sun in a well-defined pattern, the day is determined by the rate of rotation, which can vary by all sorts of factors.

It's also important to distinguish the sidereal day — a complete rotation as viewed from far away, like another star — and the solar day — what you'd actually see in terms of sunrises and sunsets if you were standing on the planet. The Earth's solar day is 24 hours, but our sidereal day is slightly shorter than that.

Mercury has a sidereal day of 58.646 Earth days, a solar day of 175.97 Earth days, and a year of 87.969 Earth days or 0.25 Earth years.

Venus rotates backwards (we think it got hit by a huge asteroid), and very slowly, so its sidereal day is 243.025 Earth days, its solar day is 116.75 Earth days, and its year is 224.701 Earth days or 0.62 Earth years.

By definition, Earth has a solar day of 1 Earth day and a year of 1 Earth year, which is 364.2425 Earth days. Our sidereal day is actually 23 hours and 56 minutes, which is 0.997 Earth days.

Mars has a sidereal day of 1.025957 Earth days, a solar day of 1.02749 Earth days, and a year of 686.971 Earth days, or 1.88 Earth years.

Jupiter has a sidereal day of 0.4135 Earth days and a solar day that is also about that length, but that's not the whole story, because the gas rotates at different speeds at different latitudes. There are actually several different "days" on Jupiter, though all around that length. Jupiter's year is quite long: 4,332.59 Earth days or 11.86 Earth years.

Saturn has a sidereal day of 0.4395 Earth days and a similar situation of varying gas rotation speeds. Its year is 10,759.22 Earth days or 29.4571 Earth years.

Uranus is even weirder because it rotates sideways at an extreme axial tilt. Its sidereal day is 0.71833 Earth days, but its solar day is 84 Earth years long at either pole, which comes from its year of 84.0205 Earth years or 30,687.86 Earth days.

Finally, Neptune has a sidereal day of 0.6713 Earth days, but, like the other gas giants, its speed varies depending on where you are. Its year is incredibly long at 164.8 Earth years, or 60,182 Earth days — the longest of all the true planets, though not as long as the recently-demoted "dwarf planet" Pluto.