Learn Polish: Ta kobieta siedzi na wygodnym krześle. - This woman is sitting on a comfortable chair.

The preposition na (on) indicates a location, which triggers the Locative case. The noun it describes, krzesło (chair), is neuter. In the Locative case, adjectives describing neuter and masculine nouns end in -ym (or -im). Since the base adjective wygodny (comfortable) has a hard consonant before the ending, it takes -ym, becoming wygodnym.

How does the dictionary word krzesło change into krześle?

To form the Locative case for most neuter nouns, the final -o is replaced with an -e. This -e causes the consonants right before it to "soften". In this word, the hard ł changes to a soft l, and the s softens into a ś, transforming krzesło into krześle.

I usually see to used for "this". Why is it Ta kobieta here?

You use the unchanging word to when introducing something, like in the phrase To jest kobieta (This is a woman). However, when "this" acts as an adjective pointing directly to a specific noun (This woman...), it must match the noun's gender. Since kobieta is feminine, you must use the feminine form Ta.

What is the dictionary form of the verb ?