Let me put it in a more systematized way. And no, it has nothing to do with tenses.
he refers only to male living beings, but in Russian
он refers both to male living beings and also to any non-living thing which is named by a noun of the masculine gender, like
звук (sound), etc. In the latter case English uses
it to refer to those things.
That is why:
– Ты помнишь Ивана? (Do you remember Ivan?)
– Да, я помню его. (Yes, I remember him.)
– Ты помнишь мой номер телефона? (Do you remember my phone number?)
– Да, я помню его. (Yes, I remember it.)
It is good is a different case. Actually, English has several meanings of
it. Apart from referring to non-living things discussed above, English
1. refer to the whole situation being discussed, like:
– I've bought a new house!
– It is good!
it refers to the friend's buying a house, in English it can also be substituted by
that ('That is good!'). In such cases both
that are translated into Russian as
это, or omitted altogether, so the dialog above is:
– Я купил новый дом!
– Это замечательно! / Замечательно!
2. introduce a new object in order to name it. Here English differentiates between singular/plural and near/far objects:
Singular: It/This/That is a lawnmower.
Plural: They/These/Those are lawnmowers.
However, Russian doesn't make any of those distinctions, and in sentences like that only
это is used in most cases:
Singular: Это газонокосилка.
Plural: Это газонокосилки.
Only when you introduce a very far-away object, you can use
вон то instead of
That is, probably, everything as for your question. Still, English has other uses of
it, like in
It is raining. or
It was an early morning. or
It was he who helped me. etc., but, when translating sentences like that into Russian,
it is omitted, and neither
это is used:
It is raining. - Идёт дождь.
It was an early morning. - Было раннее утро.
It was he who helped me. - Именно он помог мне.