Here Yahweh's arm refers to his strength. This speaks of Yahweh strengthening them as if Yahweh would use his strength to act for them. Alternate translation: "give us strength" (See: [[rc://en/ta/man/translate/figs-metonymy]] and [[rc://en/ta/man/translate/figs-metaphor]])
This understood verb "be" may be supplied. Also, the word "salvation" may be expressed with the verb "save." Alternate translation: "be our salvation" or "save us" (See: [[rc://en/ta/man/translate/figs-ellipsis]] and [[rc://en/ta/man/translate/figs-abstractnouns]])
This refers to the times when they are experiencing trouble. Alternate translation: "when we have troubles" (See: [[rc://en/ta/man/translate/figs-possession]])