This isn't meant to be a deep dive into Zoho's roles and profiles, just a straightforward introduction to a principle worth keeping in mind whenever you're setting anyone up in Zoho: only give people access to what they actually need.
Permissions control what each person in your Zoho environment can see and do. Not everyone needs to see everything, and not everyone who can see a record needs to be able to edit or delete it. Think of it like keys to a building: the cleaner doesn't need a key to the finance director's office, and giving them one anyway doesn't help them do their job, it just creates an unnecessary risk.
It's tempting, especially when a business is small or moving fast, to simply give everyone broad access so nobody ever hits a wall. The trouble is that this approach tends to store up problems for later. Wider access means more people who could accidentally (or deliberately) change or delete something important, more people whose accounts becoming compromised would matter more, and a much harder job untangling who should actually have access to what once the business has grown.
Security professionals often call this "least privilege": give each person the minimum level of access needed to do their job, and nothing more. It doesn't mean being unnecessarily restrictive or making people ask permission for every little thing, it just means being deliberate about who can see and change what, rather than defaulting to giving everyone full access because it's easier in the short term.