The speaker is worried about "them," and the poem suggests these are children, or at least people the speaker loves and feels responsible for. The opening line is quiet and a little uneasy: "In moments, I wonder for their future." Worry comes and goes, and the speaker doesn't hide it.
The middle of the poem is built on a pattern. First come three "I cannot" lines, which admit how limited a protector really is. The speaker can't shield, can't guarantee safety, can't control the choices others make. Then the pattern flips to "I can," and the speaker turns toward what is possible: being angry at the world as it is, voting, fighting, building, and believing in them. Anger here isn't bitter. It becomes fuel for action.
The mood moves from vulnerable to determined. The last line, "I will," is short and firm, like a promise. It leaves the reader with resolve rather than fear.