My Wi-Fi network is not secure, how can I protect my MacBook Air?

In these types of situations, that is when connected to an "open" or "unsecured" wireless network, I suggest that you consider the following:

• Unless absolutely necessary avoid going to financial or medical sites where you need to log into, where your data is critical to you. Of course, never go to sites that are known to be problematic.
• As BobTheFisherman has already mentioned, only access sites that are secured. Again, you would know that by seeing https in the address line or a locked symbol.
• If not already turned on, enable the macOS software firewall via System Setting. In addition, but totally optional, look into a third-party software firewall, like Little Snitch. This will provide you with greater granular control of what an app, on your Mac, is allowed to send or receive, on the Internet.
• Be sure to check your web browser's security settings to be sure that they are the most restrictive. A necessary trade-off for safety vs. performance. If you can't access a web site with these restrictions applied, you probably don't want to go there anyway.
• This is one of only two scenarios where using a "trusted" VPN will come in handy. The other scenario would be to access your work location ... where they typically provide you with this service. By trusted, I mean that you should avoid any VPN provider that offers free VPN service. However, note that paid ones are not always safe either. It pays to shop around and not always trust what a particular provider tells you about their service. The key here is two things: 1) Do they log your traffic?, and 2) Be aware that the VPN connection is only secure between your device and their servers. From their server to the website that you are trying to reach will be unsecure.

dunkof wrote:

i am in a hotel where the wifi is unsecure. how can i protect my information and computer?

What do you mean the WiFi is insecure? If so, disconnect from the WiFi. When using the Wifi to visit websites etc. use secure protocols such as https rather than insecure protocols like http.

dunkof wrote:

i am in a hotel where the wifi is unsecure. how can i protect my information and computer?

Oddly enough, Apple and pretty much everybody else solved this a decade or so ago.

Devices and computers from Apple and other vendors and mail providers and websites are using end-to-end encrypted connections; are using HTTPS and TLS.

Any claims of those marketing typically-unnecessary and too-often privacy-compromising add-on VPN services and add-on anti-malware apps aside, of course.

Some cellular network connections aren’t all that well secured, either. Though that’s been getting better.

What to do? Whatever you needed to connect to the network for…

Commercial sites like hotels, airport and such do not offer secure wi-fi access because it simpler and lower cost to let the user worry about, and provide, their own security.

You can't change how the business has set up free access; you can only "surf smartly".

dunkof wrote:

i am in a hotel where the wifi is unsecure.

That means any data sent over that network can be intercepted...

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... but Internet traffic is encrypted anyway.

In other words, so what. Go ahead and do whatever you would normally do. After all, it's not as though you are engaging in any sordid or illegal activity... right?

An open network is convenient. Otherwise, imagine all the phone calls a hotel's front desk clerk gets from guests constantly asking for their Wi-Fi network password — which they'll gleefully give out anyway. It doesn't serve any purpose.

how can i protect my information and computer?

Read Effective defenses against malware and other threats - Apple Community.