A chord is three notes played at the same time and at Grade Five you need to be able to recognise chords I, II, IV and V. Always check the root of the chord and any additional sharps or flats.
If a triad is major, its Roman numeral is always shown in uppercase (e.g. the Dominant of either a major or minor key will itself will be a major triad, referred to as V); a minor triad is shown in lowercase, such as the tonic triad of a minor key (‘i’) or supertonic (‘ii’) of a major key.
A triad that is Diminished (comprised of two minor thirds, such as the supertonic of a minor key) is often shown in lowercase but also with an asterisk to distinguish it from a minor triad, thus: ii*.