When a digit can go only in the same two columns in each of two rows, no other cell in those columns can hold it.
Where to lookA pointer first: look at row 8. Where can 4 still go?Locked candidatesIn row 8, 4 can only go in column 1, column 2, or column 3, and those three cells lie in the bottom-left box. So no other cell in the bottom-left box can be 4.X-WingIn row 5 and row 8, the 8s all lie in column 5 and column 9. So 8 can go nowhere else in column 5 and column 9.
Pick a digit and find two rows where it has exactly two places, in the same two columns. The digit takes one column in each row, so both columns are used up by those rows. Remove it from the other cells of the two columns. Swap rows and columns for the other direction.
This example, step by step
Where to lookA pointer first: look at row 8. Where can 4 still go?
Locked candidatesIn row 8, 4 can only go in column 1, column 2, or column 3, and those three cells lie in the bottom-left box. So no other cell in the bottom-left box can be 4.
X-WingIn row 5 and row 8, the 8s all lie in column 5 and column 9. So 8 can go nowhere else in column 5 and column 9.
In hints
The hint first gives a direction: those two rows. Blue ground marks the rows, blue marks where the digit can go, and orange strikes remove it from the other cells of the two columns.