His briefs here are the design instructions, not his briefs, like his underpants.

这里的 briefs 指的是设计说明，而不是他的三角裤（briefs 有“内裤”的意思），也就是内裤。

In such processor designs, instructions can be any number of bytes long, which makes the fetch cycle of the CPU a tad more complicated.

在这样的处理器设计中，指令的长度可以是任意字节数，这使得 CPU 的获取周期稍微复杂一些。