Sigo leyendo novelas en español en la biblioteca para ampliar mi vocabulario.

I keep reading novels in Spanish in the library to expand my vocabulary.

Breakdown of Sigo leyendo novelas en español en la biblioteca para ampliar mi vocabulario.

• yo: I
• en: in
• leer: to read
• mi: my

Questions & Answers about Sigo leyendo novelas en español en la biblioteca para ampliar mi vocabulario.

Why does sigo mean I keep / I continue here? What verb is it?

Sigo is the 1st person singular present form of seguir (to follow / to continue). In the structure seguir + gerundio, it commonly means to keep on doing / to continue doing:
Sigo leyendo = I keep reading / I’m still reading.

What exactly is the grammar of sigo leyendo?

It’s the periphrasis (verb phrase) seguir + gerundio:

• seguir conjugated (here: sigo)
• • gerundio of the main action (here: leyendo from leer)
    It highlights an action that is ongoing or repeated/continued over time.

How is leyendo formed from leer, and why is it irregular?

The gerund of many -er / -ir verbs is -iendo, so from leer you’d expect leiendo, but Spanish changes -e- + -iendo to -yendo to avoid awkward vowel combinations:
leer → leyendo (same pattern as oír → oyendo).

Could I say estoy leyendo instead of sigo leyendo?