This question is easy to solve long as you know the vertical uprights mean to "take the absolute value".
To take the absolute value of a number, simply make it positive if it is a negative number and do nothing if the number is positive.
I don't see an operator between the first '2' and the first '|' so I'm assuming it is multiplication. Is there is an operator there and forgot to put it there, then I'll edit this answer to give the correct answer.
2 * |2 - 4| + 6 # Starting expression
2 * |-2| + 6 # Subtract 4 from 2
2 * 2 + 6 # Absolute value
4 + 6 # Multiplication
10 # Addition
Hope this helps!