Titta bakom dig, en apa med tre huvuden!
A noble attempt, but that's "Det är det näst största aphuvudet (som) jag någonsin har sett!" (Much like "that" in English, the "som" is optional here.)
- "Huvud" is an ett-word, not an en-word. "Apa" is indeed an en-word, but the true subject here is the head. It just happens to belong to the monkey.
- "Andra" means "second" as in that it's number two in a sequence. "Second" in the comparative sense is "näst".
- "Monkey head" is a compound word and as such needs to be combined into one in Swedish. We take our compound words very seriously in Swedish ;-) For example, the difference between "rökfritt" and "rök fritt" is that the first means that something is free of smoking. The second means that people are free to smoke as much as they want. They're functionally opposites.
- As I've previously mentioned, "huvud" is an ett-word, so the definite singular is "huvudet". "Huvuden" is actually "heads", plural.
- "Ever" is "någonsin". "Aldrig" is "never".
- I can't tell you the exact grammatical reason, but "någonsin" comes before "har" here.