No "it's" in Hebrew
The examples above were with nouns, and what if I want to use an adjective? For example - "it's hot today"? Here - it's tricky. Here is the classic case in which I'd omit the "it's" and say just חַם הַיּוֹם. Adding זה would be very unnatural in this case. It's not a big mistake, but it just sounds kind of wrong. :)
Especially unnatural it is when the adjective is followed by a verb:
נֶחְמָד לָשֶׁבֶת בַּמִּרְפֶּסֶת עִם חֲבֵרִים - It's nice to sit on the balcony with friends
קָשֶׁה לַדָּבָר אִתּוֹ - It's difficult to talk to him
טוֹב לִקְרֹא סַפָּרִים - It's good to read books
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*Disclaimer - sometimes we DO use זה before adjectives! It's not a 100% rule!
However, my advice for learners - to be on the safe side - a rule of thumb for you - just don't use "it/this" before adjectives (good, bad, nice, etc..) - and you'll never be wrong! :D