Pitch: the frequency (in Hertz or Hz) in which your voice is sung. If you're unsure which pitch your voice falls on when you sing, it's best to use a tuner vst plugin. One such plugin that works on most DAWs is
http://www.gvst.co.uk/gtune.htm The average tuner uses Standard/Concert pitch based on a piano. C4 or Middle C is 261.626Hz for instance.
DAWs that come with tuners preinstalled are
Mixcraft (proprietary for non-trial) and
Studio One (has a fully functional unlimited time free version).
Multipitch: When a voicebank is recorded in more than one pitch. Pitches are labelled in the alias as suffix such as +, -, ↑, A#4, etc. (for ex. ba G4) and then assigned through the prefix map. This is done to assist in realism and helps the UTAU engine transition the voice through different vocal registers (low/chest [depending on your voice type, this can be in the 2nd or 3rd octave but I'm basing this around the soprano voice type since I'm most familiar with it], middle/mix [upper half of the 4th octave], high/head/falsetto [5th and 6th octaves], whistle [7th octave]). This recording method is also used to minimize the metallic or noisy twang from the engine when the voice is used beyond the recommended logical range.
Mono or Single Pitch is a voicebank done on a single note. It - along with the CV recording method - is the most common bank type due to its small size and ease of use for those new to using UTAU (note: while it is easy in that the average user can fit a ust to a voice and plug n play, single pitch CV is harder to make sound smooth in transition between notes and achieving a smooth sound through oto configuration is more difficult than with CVVC or VCV. It is also more prone to engine noise due to lack of transitional pitches [which is where multipitch comes in]).