Before covid and being in office - "core hours" meant you needed to physically be in office during those hours on almost all days - basically all work days except occasional doctor/dentist/signing-contract-to-buy-house/sick type of situations. And had flexibility to come in earlier or stay later.
In your case it seems to be the same definition of core hours.
Or this "trust to balance their work and life" means it would really be OK for someone to say something like "I'm regularly pick up kids from school/daycare during those last 2 core hours"?