Direct explanation
In this instance, the dash provides a direct explanation of what the speaker means when he or she says "condiments".
Context clues are basically hints writers provide when defining or elaborating on a word. A dash or colon is a popular type of context clue.
In the sentence "...pack the condiments- the salt, pepper, catsup, mustard and mayonnaise", the context clue is denoted by the dash following the word "condiments".
