What does a Tenancy Agreement letter look like?

You can search in Google, see if anyone posted their agreement copy online.

It's typical a two pages or more document which covers the agreed liabilities, conditional clauses and rental payment date, which needs to be signed by the land lord and the tenant with a witness. Thanks

Note: Yes, you can consider it legally.

Officially, any tenancy agreement must be stamped by the authorities (and the stamp duty paid by the tenant) for it to be legally valid.
The rule is not universally enforced, though, and many tenants/landlords prefer to save the money and forgo the legal certainty this brings.

I see, Is there any regulation for the minimum lease time for HDB/Private Condo?
Like it should be 6 months lease at minimum for HDB?