Let's break down the meaning of each section to provide a broader context to work from: a) trade: by definition, trade means to exchange; to give in order to receive. Example, "I traded my iPhone for an iPad." b) away: by definition, away means to leave, to be absent. c) for: this is a preposition which, in this case, means "in place of," "instead." For example, "I will substitute bread for rice." I don't have rice so I will substitute bread. d) high-end: meaning high quality. e) capability: the power to do something Now, to bring it all together: Trade away size = allow size to 'leave," to diminish greatly but to be replaced (i.e. traded) for something else For: preposition to show what will be replaced High-end capability = powerful performance (processing, speed) In other words, the size will become smaller so we can allow performance to increase.