MYDBA@ORCL > 
MYDBA@ORCL > create or replace procedure myproc(p_table_name varchar2)
  2  is
  3  	     sqltxt varchar2(200);
  4  	     l_count pls_integer;
  5  begin
  6  	     sqltxt := 'select count(*) into :result from ' || p_table_name;
  7  	     dbms_output.put_line(sqltxt);
  8  
  9  	     execute immediate sqltxt into l_count;
 10  	     dbms_output.put_line(l_count);
 11  end;
 12  /

Procedure created.

MYDBA@ORCL > 
MYDBA@ORCL > exec myproc('all_objects');
select count(*) into :result from all_objects
39214

PL/SQL procedure successfully completed.

MYDBA@ORCL > exec myproc('all_tables');
select count(*) into :result from all_tables
117

PL/SQL procedure successfully completed.

MYDBA@ORCL > 
MYDBA@ORCL > drop procedure myproc;

Procedure dropped.

MYDBA@ORCL > 
MYDBA@ORCL > set echo off;