When you place outbound links on your website, you're sending your readers to an external website. Make the links open in a new tab so you don't lose visitor. Outbound links are different than internal links, which you should also use when appropriate. You can have follow and nofollow outbound links, but you should use follow outbound links. If you don't feel it's relative to your readers or a trustworthy link, you shouldn't be linking to it.
You can tell if a website is safe to link to by looking at the organization running the site to see if they have a good reputation. The page you're linking to should be well written and free of obvious errors. The author should be a credible source. You also want to link to a fairly recent article, not one published years ago, unless you're taking an evergreen idea from the article, not outdated statistics.
Link to reliable sources; they deserve it. You would want someone to link to you if they found your site helpful. If you reference a source, always link to it. It builds your authority, which can indirectly help with SEO. Would you want to read an article which cited statistics the author didn't back up with a reputable source?
Some publishers worry that they shouldn't link out at all, fearing it can hurt their SEO. It can't, unless you link out to another site in every other sentence. If you do, your site will look like a link farm. Also, if you must link to almost everything, the article is too advanced for your visitors. If you are linking to a website you found very helpful, you may want to message the publisher and tell them you have linked to them. They may want to link back to you. For more information click here https://www.reddit.com/r/SEO/comments/hujl7j/howmanyoutboundlinksistoomanforablogpost/.