When speaking, if words don't come to mind, it's pointless.
When speaking, if words don't come to mind, it's pointless.
話すときに 単語が頭の中に浮かんで来なければ 意味がない
it's pointless とは 意味がない、無駄だと言う意味です。it's meaningless, there's no point もそうです。この文でどちらでも使えます。
When speaking, if words don't come to mind, there's no point.
When speaking, if words don't come to mind, it's meaningless.
to come to mind は直接に「頭・脳・覚え に来る」の意味で浮かぶ、浮かんで来る になります。