Я медленно спускаюсь по лестнице.

I am slowly coming down the stairs.

Breakdown of Я медленно спускаюсь по лестнице.

• я: I
• медленно: slowly
• лестница: the stairs
• спускаться: to come down

Questions & Answers about Я медленно спускаюсь по лестнице.

Why is the verb спускаюсь and not спускаю?

Because спускаться / спуститься is the verb meaning to go down / to descend oneself.

• Я спускаюсь = I am going down
• Я спускаю would come from спускать, which usually means to lower something or to let something down

So:

• Я спускаюсь по лестнице = I am going down the stairs
• Я спускаю чемодан по лестнице = I am lowering / taking the suitcase down the stairs

The ending -юсь here is the 1st person singular present-tense form of the reflexive verb спускаться.

What does -сь / -ся mean in спускаюсь?

The -ся / -сь ending often makes a verb reflexive, but in many cases it is just part of the dictionary form of a verb and gives it a specific meaning.

Here:

• спускать = to lower something
• спускаться = to go down, descend

So in this sentence, -сь is not really translated as myself in English. It is simply part of the verb спускаться.

The -сь form appears instead of -ся because it comes after a vowel:

• спускаю + сь → спускаюсь

Why is it по лестнице? Why use here?