This value refers to how divisible your token can be. It can be configured to better represent the specifics of your token.
For example, if you wish your token to be completely indivisible (and thus only be distributed in whole numbers), set decimals to 0.
Any other value would represent the amount of symbols that this token can have after the decimal point (i.e. 5.000 if decimals is set to 3).
By default decimals are set to 18.
If you check the Freeze transactions box while creating your contract, you will be provided with an option to stop all transactions involving the token at any time later. Neither you nor any of the token holders will be able to move the tokens.