To see limiters in the databases, look on sidebars, toolbars, or click on a "search options" or "advanced Search" links.
Full Text brings up articles that include the full text of the article. If you don't check this box, articles may appear that only include the citation information -- not the full article, and then you would have to get the full text article somewhere else. But if you really want that article, you could try searching for it in a different database, or sometimes we can get the article from another library through Interlibrary Loan.
Scholarly (Peer Reviewed) Journals are articles that have been reviewed by other experts in the field. Sometimes it may be a requirement of your assignment to only use peer reviewed journals.
Published Date allows you to specify a date range. Depending on your topic, date may be very important. For instance, you may want to limit to the last (5) years if you have a medically related topic, whereas date is not as important if your topic is literature or history based.
Other limiter options could include format type, publication type, language, location, etc.
Limiters are basically options you can choose to narrow your focus. You can choose more than one limiter at a time. To see these options, look on sidebars, toolbars, or click on a "search options" link or something similar.
When you "Search Everything" using One Search, look for the limiters on the left sidebar.