In Paganism cleansing it used to clear a place, item or person of energies (usually bad, but for arguments sake I’d just say ‘energies in general’) it’s a term you’ll hear most in Wicca but it’s used in other traditions as well.
I’m not going to give you a specific ritual, I don’t adhere to any in my own practises and there are plenty of resources out there for those of you who are looking for one- this is just a run down of things you can use to cleanse.
Firstly I’d say that most cleansing of objects is generally done when the moon is new, though again it depends on your own personal beliefs and traditions as to whether you follow that. Also, spaces are mostly cleansed in a clockwise direction.
Cleansing is important in the modern world as we’re often using items or performing rituals in spaces that have multiple uses, and over time the energy gets clogged up. I think it also helps you mentally to see the object or place as something sacred rather than letting your mind slip to what they are when you normally use them.
SALT is a pretty traditional thing to cleanse with, you can use it on its own and rub it on things or sprinkle it around a space (indoors please!) to cleanse it. You can also wash with it to cleanse yourself.
WATER either in the traditional form of a bath/shower (I like a cold shower before a ritual) or you can bless it and use it to wash items or sprinkle around the area, you can also combine it with salt for this.
CRYSTALS I’m not a crystal person but I’m pretty sure clear quartz can be used for cleansing purposes (don’t quote me, I’m a couple of places behind Wikipedia on the reliability scale.)
SAGE we all know that sage is great to smudge with (learn all about smudging here!) but you can also stick it in your bath and have a good wash with it too.
BROOMs can be used to physically sweep bad vibes away from the area that you’re going to be working in.
FIRE can be used in the form of white candles carried around the space, you can also use it to cleanse blades by passing them through the flame (just the blade part, keep your fingers away from the fire part.)
INCENSE (SANDALWOOD, FRANKINCENSE, ROSEMARY, SWEETGRASS) you can burn it in the space, pass objects through the smoke or put the herbs in your bath.
HANDS can also be used if you want, just close your eyes, visualise the energy surrounding you/the object/the place and physically ‘pick’ away the bad energy.
Taking a ritual bath: http://paganwiccan.about.com/od/imbolcmagic/ht/ImbolcBathRitual.htm
Cleansing your energy: http://www.paganspath.com/meta/protcn.htm
An object cleansing ritual: http://www.paganspath.com/magik/clearing.htm