Final answer:
Ulla represents an enigmatic allure and the possibility of a wider world to Gerda, inspiring her to learn English to expand her horizons despite potential dangers, reflecting a desire to control her own destiny similar to Nora's decision in 'A Doll's House'.
Step-by-step explanation:
Ulla represents an enigmatic and distant beauty to the young Gerda, possibly symbolizing a world of possibilities and experiences unknown to Gerda. As Ulla comes from a background of mystery and the strange wonders of the North, Gerda might see in her an allure of the foreign and the romantic, contrasted against her own mundane life.
The decision to learn English, despite the risks involved, could be Gerda's way of seeking to break away from her own limitations and to reach out for a broader horizon, one that Ulla's presence has perhaps made more tangible for Gerda.
The dangers of learning English may reflect the societal constraints or personal dangers (either physical or emotional) that Gerda has to navigate through, but her determination to do so implies a strong desire to grow beyond her current circumstances and to seize control of her future, much as Nora did in Henrik Ibsen's play 'A Doll's House' by choosing to leave her husband and children to educate herself and to seek independence.