What does the coalesce command mean in this Splunk search?

Merging Data Fields with Splunk Coalesce Command splunk coalesce coalesce eval remote_host = replace ( remote_host , d + $ , ) coalesce معنى coalesce The first value that is not NULL, coalesce(null(), Returned val, null()) cos, Cosine of X, n=cos #12 exact

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