Surprisingly, most of the planets in our Solar System can be observed with the naked eye at times which are ideal for viewing in each case. Mercury is not easy to see since it is usually close to the sun and is a very small planet, but it is bright because it is close, and it can be observed under the right conditions. Venus, Mars, Jupiter and Saturn are usually easy to spot when within range for viewing.
Since planets orbit the Sun, they aren't always where we can see them, but these four stand out when they are in a good position. Uranus is the most distant planet that can be seen by the naked eye. It is a gassy giant planet, but like Mercury, it can be difficult to find because it is so far away. Neptune, another gassy giant, is beyond range for viewing by the naked eye, but can be seen with a good telescope or binoculars. The dwarf planet Pluto is tiny compared to the rest of the planets and can be seen only with a fairly powerful telescope in a fully dark sky.
For the best success in viewing our planetary neighbors, a star chart or map is a must! You can find some of these online, and there are even apps for your smartphone that will help you spot those heavenly bodies.