A sparse bundle is a container file system. That is to say, it is a file that has a file system inside.
Often times they are used for backups. Although the backup is generally on an external device.
Another use in old versions of Mac OS X were as File Vault 1 encrypted containers for all your user data.
So a lot would depend on exactly what this sparse bundle was. If it happens to be a File Vault container with all your user data it would be a bad idea to delete it.