What is the meaning of 得 in 饿得受不了?
得 in 饿得受不了 is a 'degree particle' that indicates what 'degree' the adjective is at.


饿 = hungry
饿得 = hungry to the point of
饿得受不了 = hungry to the point of cannot endure (unbearably hungry)


another example


快 = fast
快得 = fast to the point of
快得像闪电  = fast to the point of like lightning (lightning fast)