What are the academic job ranks in Sweden?
In general, «Universitetslektor» is the closest the Swedish system has to an «associate professor» in the US system, and is close to a «lecturer» in the British system. The more junior rank would be «Biträdande lektor», and the more senior «Professor».

There are some subtleties in play here though; most importantly for the linked position is the phrase «tidsbegränsade anställningar». This means that the position is for a limited time only — they are hiring from March to December, supposedly to fill an urgent teaching need. The limit in time signals several things. One of them is that it is likely to be important to shoulder the teaching required — it might, depending on the department and their situation, for instance be difficult to buy out teaching time with research funds. Another is that it comes with none of the tenure guarantees usual «lektorat» provides. Since the position is time-limited, it will evaporate at the end of the time, to be replaced with a different position if the department finds the funds to hire again.

The hierarchy to figure out how the ranks work would be something like:

Tidsbegränsad anställning: Time-limited appointment. Not subject to tenure-like employment protection.

Adjunkt: Adjunct teacher. Needs not have a doctorate. Fills a teaching need.

Biträdande lektor: Similar to tenure track; usually time-limited to 4-6 years, at the end of which a review takes place deciding whether to upgrade the position to...

Lektor: The most common of Swedish University teaching/research positions. Obligated to teach, but can usually trade teaching time against research grant money. At every University I have ever interacted with, these come with an obligation for a certain amount of pedagogical qualifications — and if you are hired without pedagogical coursework in your CV, you may have to spend large swathes of your first year studying higher education pedagogy.

Professor: Similar to Professor in the UK or Full or even Named professorships in the US. It used to be very rare — one or two per field wasn't uncomomon; but since 1999, Professor is a possible target for promotion from Lektor, which increases the numbers. Before the 1999 reform, a Professor could not be fired, even under usual Swedish employment protection rules.

In summary: «Universitetslektor» is an essentially tenured position. They all come with heavy-looking teaching loads, but it is common in Sweden to reduce teaching loads with grant money. «Tidsbegränsad anställning» is a non-tenured and likely to be teaching-heavy position.