Used to introduce a comparison or analogy (literally, 'if one were to compare'); functions like 'for example' or 'to illustrate'.
例えるなら、この新しい薬は古い鍵と合う鍵穴を変えるようなものだ。
To put it simply, this new drug is like changing the lock so the old key fits.
彼の説明は少し難しい。例えるなら、複雑な機械の中身を一つずつ見ていくような説明だ。
His explanation is a little difficult. To compare, it's like explaining the inner workings of a complex machine piece by piece.
例えるなら、彼女の歌声は夜空に光る一つの星のようだ。
If I were to compare, her singing voice is like a single star shining in the night sky.