In ISO 45001:2018 clause 4.1, context of the organization is understanding the internal and external issues that affect your ability to implement and maintain your OHSMS. Do you have an internal culture of safety or not? This would be an internal issue. A supplier notifying you that they are stopping production of a cleaning chemical you use (where the replacement is more hazardous) would be an external issue. This helps you to understand your organizational context; how it fits into the world around you.