You mean safe from the developer who is coming to work on it? or safe from hackers online?
If you know nothing about general website management, it will be tough...
If your website is simple html / css / php without database, just a frontend catalog type of website, then its easy for you, just keep the backup of the website and whenever something happens to it, delete everything in your public_html folder in FTP and upload your backup. then change all the passwords, CPanel, FTP etc..
Since WordPress is most popular CMS and it powers almost half of the websites online, Im gonna assume you have a wordpress based website.
Here is some very basic tips to keep it safe, but trust me, these basic tips can keep you safe on a long run, unless someone will try to specifically target your website.
1) Start using strong passwords on everything - CPanel, FTP, WordPress admin panel.
2) Do NOT, I repeat, Do NOT use "admin" username.
3) Search for several of the plugins that disable WordPress Meta Generator, there are lots of scripts that crawl the web looking for WordPress websites. If they dont know you use wordpress, thats already excluding your website from thousands of lists of potential targets to hack.
4) Install a good security plugin. I like using All In One Security Firewall (by the way, this does take care of WordPress Meta Generator Issue), google for tutorials on settings for this plugin.
5) Keep your plugins & the WordPress core up to date. Always update them.
6) Do not install unnecessary plugins, delete the ones that you dont use anymore.
7) Make sure, your theme has debug settings set to OFF.
8) Use a good CDN, or at least use free cloudflare.
9) Good caching will take you far.
10) Minimize your CSS & JS files and load them from outside of wp-content/your-theme folder. One more and very good way to hide that you are using WP, after removing the WP Meta generator.
11) If you dont need it, disable user registration and trackbacks.
12) Use a well coded theme.
13) change the default login URL of WP.
14) install and configure backup plugin. I backup DB daily and the whole website weekly. There are several plugins that can do this for you and send backups to google drive or dropbox.
15) Install good anti spam plugin and monitor your comments - or disable them if you dont need it.
From the top of my head, these are the basic and good steps to take. I'll add on if I remember something else.
If you dont have WordPress, these tips might help someone else anyways.
Stay safe and good luck