。
I run as fast as Jim.
Literal
I [topic-は] Jim [with-と] same-amount run [nominalizer-の-が] fast.
The equal-comparison pattern [AはBと同じくらい+adjective] means 'A is as [adjective] as B.' と marks Jim as the standard of comparison ('as... as'), and 同じくらい ('the same amount/extent') does the comparative work. The 走るのが nominalizes 'running' to become the grammatical subject of 速い ('fast').