Jazz musicians especially like `unusual' chords and harmonies and as you would expect they use a rich variety of chords and stretch the notation as far as it goes. Here is a quick introduction to some of the more advanced chords.
The 5 chord is a major chord missing the third. I am not so sure that 2 notes count as a chord but there you are. An example is A5 which is make up of the notes A and E.
The thirteenth is an extension of the eleventh with the addition of the note at the major thirteenth interval as one would expect. So A13 is made up from the notes A, C#, E, G, B, D and F#.
The 6/9 chord is made up from the keynote and the notes at intervals of a major sixth and a major ninth. So A6/9 is made up from the notes A, F# and B.
There are some more ninth chords. The major ninth (maj9) is merely an extension of the major seventh. You can also specify that the ninth is flattened with a "-". For example A11-9, A7-9 have flattened ninths and can be alternatively written as A11b9, A7b9.
The flattening notation can also be used for other intervals. For example A9-5 which has a diminished fifth. Another possibility is to add on notes (A7add2) but I don't go in for that myself since you get into arguments over chord names and inversions. Just play the notes and enjoy.