it will increase access times - which is the equivalent of saying you have more lanes on your highway - but achievable speed is still depentant on traffic - bootup and response time should generally improve too

you can compare the way a computer processes information to the way a city handles traffic, there are fast roads, slow roads, clearways and bottlenecks, and it always depends on how many processes want to travel [ have access] at the same time - so the best I could say without knowledge of your computer and what is installed and how you use it is: it will maximise the theoretical speed your computer is capable of when swapping data in and out of memory and executing data transfers; it will also eliminate one pontntial source of mechanical failure and make the computer, if it is a laptop, safer to lug around [although nothing lasts for ever, but modern SSD's are good - get one that is larger than you need for system/storage within budget constraints so there is 'headroom', and buy a reputable make, I use samsung EVO]

all that said, if your computer is long in tooth seriously consider replacing it - yes a hasstle and expense, but consider it... windows 10 is becoming less forgiving of older hardware and that affects speed also... and it save you the bother of making the changes which is never 100% risk-free

if you store TB's of data though [external] HDD is still the way to go on grounds of cost

EDIT - when I upgraded my 2014 vintage HP Pavilion laptop two years ago, I experienced the imporvement that Paul has just indicated