すな
sand
suna
JMdict 1291500
すな砂sandのうえ上aboveをあるく歩くwalk
Two particles chain the pieces together. の (of) links 砂すな (sand) to 上うえ (top) to mean “the top of the sand,” and を (object) marks that surface as what the walking crosses. The verb 歩くあるく (walk) lands last, as Japanese verbs always do.
hanamaru