Hi @nana
The Spark core does not have the resources to do HTTPS on its own; it does HTTP transfers well. The certificate management for TLS/SSL would not fit in memory. So instead it has one secure connection to the Spark cloud but you can use that connection for all sorts of things: variables that you can read from the core, functions you can call on the core, events you can publish from a core and recently even subscribe to. Check the docs and the tutorial section here in the forum for more info.
There is a way for a Google spreadsheet to pull data from the core periodically described in this thread:
There are lots other ways to do this!