Key M365 security controls: Azure AD MFA, Conditional Access policies, Defender for Office 365 (email), Defender for Endpoint, Microsoft Purview (DLP/compliance), Privileged Identity Management (PIM).
M365 is a rich security platform if licensed and configured properly. Enable MFA for all users (non-negotiable). Conditional Access = zero trust policy engine for M365. Defender for Office 365 P2 adds attack simulation training. Secure Score benchmarks your configuration.