はとても難しいです

is very difficult

→ は
phrase Rare #30,221
is very difficult The は marks the topic; the thing being described comes before it.
JA: 漢字はとても難しいです。
EN: Kanji is very difficult.

おっしゃるとおり、ロシア語はとても難しいです!

You're absolutely right—Russian is very difficult!

私にとって、英語で話すのはとても難しいです。

Speaking English is very difficult for me.

英語を話す事は私にとってはとても難しいです。

Speaking English is very difficult for me.

これはとても難しいです。

This is very difficult.

英語を話すことは私にはとても難しいです。

Speaking English is very difficult for me.

この言語の文法はとても難しいです。

The grammar of this language is very difficult.