Question regarding Function & Return table

All,

I am a beginner to learn Pl/ SQL.
How can I return either " Return Pl/SQL table" or "Return VARCHAR2"
simultaneously? The result is dependable on Count(Last_name)
condition.

Thanks,

The below is incomplete because I cannot understand the above
question.

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create or replace function New_Rental(
P_last_name  S_member.LAST_NAME%TYPE,
P_member_id  S_member.Member_id%TYPE,
P_first_name S_member.FIRST_NAME%TYPE,
P_phone      S_member.Phone%TYPE,
P_VALID_DATE In OUT Date)

Return VARCHAR2
Is 
V_msg :='Expected due date is'||P_VALID_DATE;

Begin
If Count(Last_name)=1 then
Select VALID_DATE INTO P_VALID_DATEfrom  S_memberWhere Last_Name:= P_Last_name;return 'Expected due date
is'||P_VALID_DATE;
 

ElSIF  Count(Last_name)> 1 then
Select VALID_DATE INTO P_VALID_DATEfrom S_memberWhere  Last_name:=P_last_name And Member_id:= P_member_id;return
'Expecteddue date is'||P_VALID_DATE||'Person's record as
 
follows:'||P_last_name,P_first_name, P_phone, P_member_id ;

Else Count(Last_name)=0
return 'This person needs to be registered as a member' 
End If;
End New_Rental;
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