What does seq[row] and foreach retrieve here

doubts:
i am using jaxb to convert dataframes to generate XML

sample XML:

> 
>       <MainTV CId="00090" Daier="01" AId="9255965" Amber="00019101" Re="18" EffectiveDate="1999-01-01" ExpirationDate="2010-10-31" PIndicator="Y">	
>                     -<DishTV    Cid="09390" AId="9217965" Amber="00019990101" EffectiveDate="2007-01-01" ExpirationDate="2007-06-30" Anum="206773" PId="01" Bode="000358" Alpde="XJM">
> 		<Comprod EffectiveDate="2007-01-01" ExpirationDate="2007-06-30" PId="00058" Tde="H" Lde="A65"/>
>                      </DishTV>
>      <MainTV>

this below is some code i am trying to generate the above XML fields:

 var arrm_list: Seq[Row] = rows.getAs[AnyRef]("MainTV").asInstanceOf[Seq[Row]]
 if(arrm_list!=null){
       arrm_list.foreach(maintv => {
          var maintv: MainTV = new MainTV()
		  
		  maintv.CId("_Cid")
		  maintv.AId("_AId")
		  maintv.Daier("_Daier")

what does arrm_list do here, seq row does it mean it retrieves sequence of rows and
what is instanceof[seq[Row]] and getAS[AnyRef] mean here ?

i am using spark 2.3 version and scala 2.11