One sticker on a Yamaha F335 will not have a perceptible effect on the sound of the guitar. If you covered the entire soundboard (top) with stickers, you might notice an impact on the resonance of your tone.
Most of the sound from an acoustic guitar is produced by the vibration of the top - also known as the sound board. Anything that reduces or dampens the vibration can have at least a slight effect on the sound. But as another answer mentioned, a sticker is likely to have less impact on the sound than a pickguard would. Having said that, if given an option on an acoustic guitar, I personally prefer one with no pickguard.
Stickers on the back of the guitar will have very little or no effect on the tone. But then nobody will see the sticker when you are playing.
Something you may want to consider (besides impact on tone), is the potential for some damage to the finish should you ever remove the sticker. Two things can happen. First, the glue residue will be difficult to remove after the sticker has been affixed to your guitar for some time. And the solvents you use to remove the glue residue, could also damage the finish.
Secondly, exposure to light over time will impact the color of the wood. It will "age" so to speak due to exposure to light. This is why if you remove a pickguard from an older guitar, you will see a ghost or shadow of the pickguard where the coloration of the wood will vary. So it is likely that removal of a sticker after a year or more, could leave a ghost of the shape of the sticker from a variation in the coloration of the wood - unless you only take the guitar out of it's case occasionally to minimize exposure to light.
For these reasons, adding a sticker may slightly diminish the value of the guitar, if selling it in the future is a consideration. If you plan to keep the guitar in your collection forever, and you like the sticker, and if it will enhance your enjoyment of your guitar, by all means stick it on.
PS: I like stickers too - but I put them on my hardshell guitar cases where they can't possible effect the tone, and are easier to remove with no damage to the case. That's an option for those who read this who want to compromise and have their stickers but with no negative impact on the tone or value of their guitar.