SQL SUM multiple Rows into a single Column

If there's literally only two types, you can easily do this with conditional aggregation:

select
person,
sum (case when type = 'TYPEA' then value end) as typeA,
sum (case when type = 'TypeB' then value end) as typeB
from
<table>
group by
person

SELECT T.PERSON,
SUM(
    CASE
       WHEN T.TYPE='TypeA' THEN T.Value
    ELSE 0
   END
   )AS SUM_TYPE_A,
SUM(
    CASE
      WHEN T.TYPE='TypeB' THEN T.Value
      ELSE 0
    END
   )AS SUM_TYPE_B
FROM YOUR_TABLE AS T
GROUP BY T.PERSON

In SQL Server you can also write dynamic pivot. Specially it's great when you don't know all the name of the pivoted columns.

Schema and insert statements:

create table tablename(Person varchar(50), Value int, Type varchar(50));
insert into tablename values('John',10,'TypeA');
insert into tablename values('John',10,'TypeA');
insert into tablename values('John',20,'TypeB');
insert into tablename values('John',20,'TypeB');
insert into tablename values('Steve',15,'TypeA');
insert into tablename values('Steve',15,'TypeA');
insert into tablename values('Steve',25,'TypeB');
insert into tablename values('Steve',25,'TypeB');

Query:

DECLARE @cols  AS NVARCHAR(MAX)='';
DECLARE @query AS NVARCHAR(MAX)='';

select @cols=string_agg(type,',') within group (order by type)
from
(select distinct type from tablename)t

set @query = 
'SELECT Person, ' + @cols + ' from 
(
    select * from tablename    
) src
pivot 
(
    sum(value) for Type in (' + @cols + ')
) piv
order by Person'

execute(@query)

Output:

fiddle