The options with …letters work at character level, they check if he sequence of characters appears anywhere in the n-gram including inside the %[token|tokens]%. The options with …words work at %[token]% level, they check if the whole word appears between spaces in the n-gram.

all
no additional filtering will be applied

starting with letters
type a sequence of letters which each n-gram should have at the beginning, spaces can be included

ending with letters
type a sequence of letters which each n-gram should have at the end, spaces can be included

containing letters
type a sequence of letters which each n-gram should have at the beginning, in the middle or at the end, spaces can be included

starting with word
type a word that should be the first word (or token) of each n-gram, typing cat will include n-grams with cat but not with catalogue

containing word
type a word that should appear anywhere in the n-gram including the first and last positions

ending with word
type a word that should appear as the last word of the n-gram

matching regular expressions
use %[regex|regular expressions]% for detailed filtering, the whole n-gram is treated as a continuous sequence of characters

from this list
type the n-grams to find out how frequently they appear in the currently selected corpus, the n-gram size must match the size selected above, a space must appear between all tokens, e.g. I do n't know or he 'll go