The speaker wants to be trusted with another person's secrets, promising to keep them safe. But the connection fails: the other person can only speak to the speaker's shadow, and the shadow stays mute. It's a neat image of being cut off from someone, with the message going to the wrong place.
The speaker then pictures a bleak, distant world of wind, night and stars, far from bare roots like "skeletal fingers" and a dried-up water-hole where a lone crow calls into nothing. These images suggest emptiness and abandoned hope. In the last lines the other person is silent "like a mountain," while the speaker's words "bleat" like a nervous animal. That word makes the speaker sound small and anxious. The calm of the other person seems to hide a deeper tiredness. The mood is lonely and uneasy, but also tender, since the speaker still hopes to understand.