The section https://www.w3.org/TR/xpath-functions-31/#func-map-for-each defines the function "map:for-each" and then gives the example

------------ sample code ----------------------

   <xsl:variable name="dimensions" 
                 select="map{'height': 3, 'width': 4, 'depth': 5}"/>
   
   <xsl:function name="f:make-attribute" as="attribute()">
     <xsl:param name="key" as="xs:string"/>
     <xsl:param name="value" as="xs:anyAtomicType"/>
     <xsl:attribute name="{$key}" select="string($value)"/>
   </xsl:function>
   
   <xsl:template name="convert">
     <box>
       <xsl:sequence select="map:for-each-entry(
                               $dimensions, f:make-attribute#2)"/>
     </box>
   </xsl:template>  

----------- end of sample code ----------------

which uses a function named "map:for-each-entry" instead of "map:for-each".

So the sample should be

------------ sample code ----------------------

   <xsl:variable name="dimensions" 
                 select="map{'height': 3, 'width': 4, 'depth': 5}"/>
   
   <xsl:function name="f:make-attribute" as="attribute()">
     <xsl:param name="key" as="xs:string"/>
     <xsl:param name="value" as="xs:anyAtomicType"/>
     <xsl:attribute name="{$key}" select="string($value)"/>
   </xsl:function>
   
   <xsl:template name="convert">
     <box>
       <xsl:sequence select="map:for-each(
                               $dimensions, f:make-attribute#2)"/>
     </box>
   </xsl:template>  

----------- end of sample code ----------------