Here is the whole question
cooking oils contains unsaturated fats. unsaturated fats are more healthy than saturated fats.
unsaturated fats change bromine water from orange to colourless
a scientist from a food company called veigo wanted to find the amount of unsaturated fats in cooking oils.
the scientist tested veigo's own brand of oil and oils from four other companies a, b,c and d.
the scientist used the same volume of oil for each test.
the scientist results are shown in table 3
table 3
company: test1 test2 test3
veigo 14 13 16
a 25 17 27
b 17 18 16
c 5 6 4
d 10 9 7
(a1)
describe how the bromine water is used to obtain these results

Saturated oils are oils where every carbon is sp3 hybridized and attached to two other carbons and two hydrogen. An unsaturated oil features a pi bond and a sigma bond between one or more carbons. This sigma bond interacts with Br2 by way of an addition reaction, the double bond is broken and two bromine are added to the carbon chain. The resulting structure is colorless so in a way the oil absorbs the colored Br2 into a colorless molecule. So, the more Saturated an oil is, the more Br2 it can accept and that's why Br2 can be used to detect the presence of satiated oils. While adding Br2, the solution will stay colorless as long as there are double bonds to accept it.

Hope this makes sense, if you've talked about reaction mechanisms this should be pretty straightforward.