Three short statements, each carrying a quiet sense of loss. The speaker begins with stones that have come from the sea, and they "hurt my heart." The title, "Beached," helps explain why: these stones have been left on the shore, cut off from the water that once surrounded them. The speaker seems to feel stranded in much the same way.
The second stanza shifts to a different longing. The speaker misses "the promised water in ice," which suggests water that was meant to be fluid and alive but is frozen and stuck. Something expected has not arrived, or has arrived in a form that can't move.
The last lines turn inward. The speaker's "journey is in talking / to little purpose," as if speech is the only travelling left, and it goes nowhere. The mood is bare, tired, and sad, but also honest. The poem's brevity makes the feeling seem all the more stuck and quiet.