Sum from different sheet values

I need some advice on setting up the below please.

On Sheet 1, I have a list of items which can be chosen from a Data Validation List in Sheet 2

Each item in the list on Sheet 2 has a value.

I’d like to know how I can get the column in Sheet 1 to sum the total value of the chosen items in the list according to their values in the column next to them in Sheet 2.

In the example attached, the 4 items selected have a total of 6.

What formula or functions can I use to set this up?