my macbook says it has 108.3GB used for backups. Why is that? I'm running out of GB and would like to free some space up. Thanks. BTW this is my first mac.

If you have Time Machine enabled, then those are Time Machine snapshots. They will be deleted automatically if the space is needed. You can also do this:

About Time Machine local snapshots

Time Machine Snapshots

Open the Terminal in the Utilities folder and enter or paste the appropriate command line. Press RETURN and enter your admin password when prompted. It will not be echoed. Press RETURN again.

To turn them ON: sudo tmutil enablelocal

To turn them OFF: sudo tmutil disablelocal

Note that turning them OFF will also delete all existing snapshots.

For more about snapshots see: OS X Mountain Lion- About local snapshots.

What you did was completely pointless and puts you at risk of losing data.

I have to agree with Linc Davis here. I have used those snapshots to recover files that had been damaged or accidentally deleted during periods when my laptop was away from the external drive used for Time Machine backups, hence no other backup of those files existed. Without those snapshots, the files would have been "lost." Although the "snapshots" take up some physical space, they are removed automatically so in effect, they have no real impact on disk space that is available.

About Time Machine local snapshots - Apple Support

All was explained to the OP along with the same link you decided to supply a mere 3 hours after I did. Data loss is only a concern if the user needs the snapshots because they have no other backups. Once they learn what the snapshots are, then they can decide whether to delete them.

<Edited by Host>

Kappy wrote:

Data loss is only a concern if the user needs the snapshots because they have no other backups.

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The point I was making is that when portable computers like laptops are transported away from the Time Machine backup disk, the locally stored backups can prevent data loss during the time period when some files have not yet been backed up (to Time Machine). The OP has a laptop. This is a valid point that the OP may wish to consider.

<Edited by Host>

The damage is done in this case. You can help others by contradicting such fake advice whenever you see it.