Tonight and tomorrow night, Mercury and Venus, the first two planets from the Sun, will be very, very close to each other, as within half a degree. To simulate a degree of arc, hold your little finger out at arm's length. That's close!
To see the show, go out about 30 minutes after sunset and look low in the Southwestern sky. Venus should be easy to spot as it shines at -4 magnitude. Mercury, though shining at nearly -1 magnitude, will be much harder to spot as it is so close to the Sun. For Mercury, binoculars will be useful unless you have eagle eyes. With optical aid, the show will be easy to catch tonight and tomorrow.
Additionally, the planets will remain close for the coming week or so, too.