Increasing the money supply, all other things equal, decreases the value of the currency. It's that simple. The price, or value of the currency is the net of supply and demand for that currency. Same demand, higher supply, lower value per unit.
This link argues inflation is more complicated than that, which I agree with in my opening sentence, inflation has many causes. Of course it's more complicated than that. But that doesn't change the underlying basic reality that inflating the supply on its own reduces the value of the money. Supply and demand is simple, unpacking which % of the 10% inflation experienced in an economy is caused by money printing or push-pull or supply chain disruptions is a more complex and possibly impossible to fully answer question. The complexity of answering that question is a good argument for why we shouldn't give central banks the ability to change the money supply or interest rates, as they cannot have the information required to know whether raising interest rates will fix inflation because they can't even know for sure what is even causing it. I mean, inflating the currency supply is certainly a part of it, but picking apart the other pieces is when it enters that grey area of unknowability.