It refers to the amount of advantage over all the other locations/zones/triggers tracked.

"2 points up" mean the currently tracked trigger has 2 shows/appearances above every other.

Examples below.

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Repeats:

A method betting on numbers with "2 points up" has an eligible bet when a number already has one show above the others, so a hit on it would make it have two shows above.

i.e. When all the other numbers have 1 show, and a number gets 2 shows, this number is one point above the others.
If your bet for "2 points up" on such a number, you are effectively betting for it to reach 3 shows, while the other numbers are still featuring only 1 show.

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Zones:

If the currenly larger zones are having 3 numbers, then a "1 point up" bet focuses on every number which would make a zone larger than 3.

It could be zone 4, zone 5, zone 6, etc.

As long as it surpasses the other zones by at least one.