Hello.

You don't have to trust me. Find it for yourself. Choose any security headers scanner checker. For instance, try

https://securityheaders.com/

Type there your weebly hosted web site and be shocked.

When asked weebly for help how to add/modify security web headers the answer was:

I'm sorry, but we are unable to assist with security headers. No one at Weebly will be able to assist you in modifying security headers. I apologize, I wish we could, however this simply isn't something we're able to provide support on.