There are many types of filters in circuits. A tuner on a radio basically tunes into a frequency which selects a station.
The tone control in your stereo is a filter and it allows you to set the level of base (lower frequency) and treble (higher frequency).|
There are circuits that get rid of noise in household electrical circuits. There are also circuits that are used to tune many things even microwave frequencies.
A filter is device that will pass certain frequencies while decreasing other frequencies. This would be in a passive filter.
Active filters can amplify some frequencies while decreasing others.