Help:TOC
TOC is a common three-letter acronym (TLA) for 'Table Of Contents'. On MediaWiki sites, a table of contents is included automatically on the left margin of a page just before the first headline if there are four or more 'Headlines' (primary sub-headings) in an article.
You can force a TOC in an alternate position on the left margin by placing __TOC__ at the point where you desire said TOC.
You can prevent a TOC from appearing anywhere by placing __NOTOC__ anywhere within the edit box, though there ought to be strong reasons or justification for hiding a table of contents.
If you want to force your TOC to the right margin (even with less than four sub-headings), use {{TOC right}} template in the location the TOC should appear; as shown in this article.