Hi Amy!!
An album is a great way to keep groups of your uploads together. I have an album in my Member Gallery for my 6x6 scrapbook that I did of my boys. Several people like to keep RAKs that they receive in an album, as well.
Your Member Gallery is where all of your uploads appear, even when you categorize them in their proper category by stamp set, technique, or project.
When you put uploads in an album, it will appear in the album when people go to your Member Gallery. You can choose to make the album opened or closed. In other words, you can make it so that you need a password to open the album to view it or leave it regular and everyone can view it.
I honestly don't know of many that have their albums locked, seeing as it is used as a way to keep a group of uploads together.
I hope that makes sense! Let me know if you have any more questions!