use tempdb

declare @t table (
	Skill varchar(10) not null,
	BU1 int not null,
	BU2 int not null,
	Bu3 int not null
)

insert into @t
values 
	('Skill1', 0, 0, 0),
	('Skill2', 2, 6, 0),
	('Skill3', 0, 0, 7),
	('Skill4', 4, 0, 0),
	('Skill5', 0, 7, 8)
	
;with temp as (
	select 'BU1' BU, Skill, BU1 Value from @t union all
	select 'BU2' BU, Skill, BU2 Value from @t union all
	select 'BU3' BU, Skill, BU3 Value from @t
)
select *
from temp
order by BU, Skill