Sandra Bruck makes a useful description of these here: https://forum.duolingo.com/comment/2897975/Use-of-di-a-in-and-nel-for-time-in-Italian-When-do-you-use-which
Because it's a masculine noun beginning with z. Other masculine nouns that use lo instead of il are those beginning with s + consonant. The plural for these words is 'Gli' instead of 'i'.
The in italian: • for masculine nouns: - l' when noun starts with a vowel - il when noun starts with most of consonants - lo when it starts with z, ps, pn, gn, x, y and s, but after s must be anothen consonant - in plural lo and l' turns into gli, il turns into i • for masculine nouns: - starting with vowel - l' - starting with consonant - la -in plurals - le
Zoo is masculine and starts with "z", so it's "lo zoo". Which is femine and masculine you have to learn, but nouns ending with o/e are masculine, and with a/e femine (not aways).
• Lo zoo apre a maggio.
......• [ The zoo opens in May. ]
• Lo zoo
......• [ The zoo ]
......• [ opens ]
......• third-person singular present indicative of aprire
• a maggio.
......• [ in May. ]
It is a very simple and straightforward translation.
Why "The zoo is open in May. "?????
• Lo zoo è aperto a maggio.
......• [ The zoo is open in May. ]
Can you tell us why you want to translate the phrase to "The zoo is open in May. "???
What you are asking is for the explanations for "opens" and "is open", of which you can find out on many platforms. This is e-learning of the Italian language.
Perhaps you could try to put your English translation into a translation tool of your choice and see it for yourself if it translate well.
Hope it goes well with your Italian language e-learning.
My ear could not figure out what was the spoken last word ("maggio") so I typed "Lo zoo apre a MANGIO." This was accepted but I realize it should not have been accepted. I will report but just thought it was kind of funny and wanted to let my fellow learners know...for a chuckle!!