Hello, I am new here but this is right up my alley. I am a novice home repair DIYer but work in IT, and Tech is one of my fortes.
This requires some information without getting too technical or confusing. Who is your service provider? Comcast? Verizon? Are you using their router? Do you know what the wifi standard is by any chance? Do you know if it's 801.11a/b/g or n? Newer standards are ac and ax.
Knowing that will better arm you for choices. A lot of people have already made good suggestions which I am basicallly just repeating with a little more detail. You can get a repeater or extender. It will increase your wifi signal. I have to do this as my fiber leads into the basement and the router is in the basement which is partially above ground. Yet I have a lot of interference on the upper floors and needed to add an extender. You can also use an old router if you have one on hand. Also, it won't hurt to by a repeater with a newer and faster standard llike 802.11ax. It will help you "future proof" and is backward compatble for older standards - meaning say your router and all your wifi cards in your laptops, phones, and desktops are all 802.11n. It will seamlessly work with your existing network.
In networking, it basically works as fast as the weakest link. That's all the newer standards are - they have greater range and faster speeds. So if you get an AC repeater, it will just downgrade to the N speeds of your network. Hopefully I am not being too detailed or confusing. I try to explain things as best as I can.
Here are 2 goodexamples:
TP-Link has this affordable and small unit for around $25
https://www.newegg.com/tp-link-re220/p/N82E16833704487
View attachment 26035
Asus RP-AC1900 wifi extender
https://www.newegg.com/asus-rp-ac1900/p/N82E16833320392
View attachment 26036
This Asus is similar to the one I use - mine is an older model. It is more expensive and currently out of stock but due back in soon. Also, it has a coupon code attached to it for like 25% off. It is more robust powerful and fully featured, but might be unnecessary for your needs. It depends on your current network, needs, etc,
Hope this helps. Definitely update us on what you do. I'll be around if you have any question. I am new here but hope to learn a lot and help as I can.
Cheers,
Kenji