[en] The process of star formation is well known in a general aspect, however, a lot of details are still missing. Some questions, such as the mode and efficiency of the accretion process or the role of the magnetic field, are still open and are key to completely understand star formation. The aim of this work is to put constraints on some of the physical and chemical processes happening in a young star forming core during the first stages of the collapse. For this purpose, we obtained high angular observations of the Class 0 protostellar object B335. This object, which is an isolated Bok Globule, is very well known as it is an excellent source to test theories of gravitational collapse during the low-mass star formation process. It has also been suggested as a good example of magnetically regulated collapse, as it presents a strongly pinched magnetic field morphology. Within the project, we obtained dust continuum and several molecular lines emission, probing scales from the envelope, around 4000 au, to the most inner part, at around 150 au, with the ALMA interferometer. Our data set has probed to be very heterogeneous in nature as well as to present complex gas kinematics, observed in complex molecular line profiles. Within our observations of rare isotopologues from CO, we observed double-peaked line profiles which could not be attributed to optically thin lines, as expected from the abundance of those molecules. We also studied the morphology of the line profiles at different offsets of the source, and found that they were not in agreement with the expected models of symmetric spherical collapse. We use these facts to study the infall modes on the source and modeled the line profiles to obtain the main parameters, such as the peak velocity, the velocity dispersion and the opacity. From this we found that the observed emission was optically thin, and that each component of the double-peaked line profile had a line width typical from infall motions. This lead us to propose that the two peaks were coming from two different gas reservoirs with different kinematics, i.e. we propose that the collapse is not symmetric and it is occurring along the exterior of the cavity walls. Since the double-peaked profiles appeared in other CO derivatives, such as HCO⁺ and DCO⁺, we kept this hypothesis of the two distinct velocity components to proceed with the derivation of the deuteration and the ionization fraction. Our values of the ionization fraction show that B335 lies in the upper range of the values computed from the literature for protostellar objects. Since we resolve the maps of the ionization fraction, we can see different tendencies that point to different ionization processes, i.e., ionization due to Cosmic Rays, probably enhanced due to the isolation of the object and the presence of an organized magnetic field, and ionization due to accretion radiation close to the protostar. We also compare the distribution of the ionization with the polarized dust emission, which is indicative of the morphology of the magnetic field. A good correlation is observed, where the largest values of the ionization fraction are correlated with the polarized continuum intensity. We also attempted for the first time to compute the effect of ambipolar diffusion in a Class 0 object, i.e., difference in the kinematics of neutral and ionic molecules. We were able to observe that both type of molecules present different ranges of the velocity dispersion, which suggests that the ions are coupled to the magnetic field. In summary, a better view of the interplay between the gas and the magnetic field is obtained, suggesting a good coupling of the two and pointing to the fact that collapse in B335 is strongly magnetically regulated. (author)