Sometimes a single sentence carries a whole feeling, and this one does. The speaker is looking ahead to a time when they will share a bed with someone they love. For now, they sleep alone. The wall is what they find when they turn over in the dark, and it stands in for loneliness.
The speaker doesn't talk about grand gestures or big declarations. What they long for is small and ordinary: rolling over half-asleep and finding a person there. That choice makes the wish feel honest. Love shows up as comfort and familiarity, the kind of closeness you don't even have to be awake for.
The mood is tender and quietly aching. "I can't wait" sounds eager, almost giddy, but the image of the empty wall underneath it hints at how much the speaker misses having someone close. Hope and loneliness sit side by side here, and the poem lets both be true.